[PATCH v9 0/6] MCS Lock: MCS lock code cleanup and optimizations

[PATCH v9 0/6] MCS Lock: MCS lock code cleanup and optimizations

[Tim Chen]

This update to the patch series now make mcs_spin_lock and mcs_spin_unlock
as inlined functions for better efficiency in the hot path.  We order the
files in the architecture of each Kbuild before we add mcs_spinlock.h for
hooking in architecture specific arch_mcs_spin_{lock,unlock}_contended
functions.

Peter, please review the last two patches and bless them with your
signed-off if they look right.

This patch series fixes barriers of MCS lock and perform some optimizations.
Proper passing of the mcs lock is now done with smp_load_acquire() in
mcs_spin_lock() and smp_store_release() in mcs_spin_unlock.  Note that
this is not sufficient to form a full memory barrier across cpus on
many architectures (except x86) for the mcs_unlock and mcs_lock pair.
For code that needs a full memory barrier with mcs_unlock and mcs_lock
pair, smp_mb__after_unlock_lock() should be used after mcs_lock.

Will also added hooks to allow for architecture specific
implementation and optimization of the of the contended paths of
lock and unlock of mcs_spin_lock and mcs_spin_unlock functions.

The original mcs lock code has potential leaks between critical sections, which
was not a problem when MCS was embedded within the mutex but needs
to be corrected when allowing the MCS lock to be used by itself for
other locking purposes.  The MCS lock code was previously embedded in
the mutex.c and is now sepearted.  This allows for easier reuse of MCS
lock in other places like rwsem and qrwlock.

Tim

v9:
1. Inline mcs_spin_lock and mcs_spin_unlock for better efficiency in hot paths.
2. Sort files in each architecutre's Kbuild before adding mcs_spinlock.h.

v8:
1. Move order of patches by putting barrier corrections first.
2. Use generic-asm headers for hooking in arch specific mcs_spin_lock_contended
and mcs_spin_lock_uncontended function.
3. Some minor cleanup and comments added.

v7:
1. Update architecture specific hooks with concise architecture
specific arch_mcs_spin_lock_contended and arch_mcs_spin_lock_uncontended
functions.

v6:
1. Fix a bug of improper xchg_acquire and extra space in barrier
fixing patch.
2. Added extra hooks to allow for architecture specific version
of mcs_spin_lock and mcs_spin_unlock to be used.

v5:
1. Rework barrier correction patch.  We now use smp_load_acquire()
in mcs_spin_lock() and smp_store_release() in
mcs_spin_unlock() to allow for architecture dependent barriers to be
automatically used.  This is clean and will provide the right
barriers for all architecture.

v4:
1. Move patch series to the latest tip after v3.12

v3:
1. modified memory barriers to support non x86 architectures that have
weak memory ordering.

v2:
1. change export mcs_spin_lock as a GPL export symbol
2. corrected mcs_spin_lock to references


Jason Low (1):
  MCS Lock: Optimizations and extra comments

Peter Zijlstra (2):
  MCS Lock: Order the header files in Kbuild of each architecture in
    alphabetical order
  MCS Lock: Allow architecture specific asm files to be used for
    contended case

Tim Chen (1):
  MCS Lock: Restructure the MCS lock defines and locking code into its
    own file

Waiman Long (1):
  MCS Lock: Barrier corrections

Will Deacon (1):
  MCS Lock: Allow architectures to hook in to contended paths

 arch/alpha/include/asm/Kbuild      |   5 +-
 arch/arc/include/asm/Kbuild        |   7 ++-
 arch/arm/include/asm/Kbuild        |   3 +-
 arch/arm64/include/asm/Kbuild      |   5 +-
 arch/avr32/include/asm/Kbuild      |  39 ++++++-------
 arch/blackfin/include/asm/Kbuild   |   5 +-
 arch/c6x/include/asm/Kbuild        |   3 +-
 arch/cris/include/asm/Kbuild       |   3 +-
 arch/frv/include/asm/Kbuild        |   3 +-
 arch/hexagon/include/asm/Kbuild    |   7 ++-
 arch/ia64/include/asm/Kbuild       |   5 +-
 arch/m32r/include/asm/Kbuild       |   3 +-
 arch/m68k/include/asm/Kbuild       |   5 +-
 arch/metag/include/asm/Kbuild      |   3 +-
 arch/microblaze/include/asm/Kbuild |   5 +-
 arch/mips/include/asm/Kbuild       |   3 +-
 arch/mn10300/include/asm/Kbuild    |   3 +-
 arch/openrisc/include/asm/Kbuild   |   9 +--
 arch/parisc/include/asm/Kbuild     |  27 +++++++--
 arch/powerpc/include/asm/Kbuild    |   6 +-
 arch/s390/include/asm/Kbuild       |   3 +-
 arch/score/include/asm/Kbuild      |   3 +-
 arch/sh/include/asm/Kbuild         |   7 ++-
 arch/sparc/include/asm/Kbuild      |   9 +--
 arch/tile/include/asm/Kbuild       |   3 +-
 arch/um/include/asm/Kbuild         |  30 ++++++++--
 arch/unicore32/include/asm/Kbuild  |   3 +-
 arch/x86/include/asm/Kbuild        |   1 +
 arch/xtensa/include/asm/Kbuild     |   3 +-
 include/asm-generic/mcs_spinlock.h |  13 +++++
 include/linux/mcs_spinlock.h       | 114 +++++++++++++++++++++++++++++++++++++
 include/linux/mutex.h              |   5 +-
 kernel/locking/mutex.c             |  60 +++----------------
 33 files changed, 275 insertions(+), 128 deletions(-)
 create mode 100644 include/asm-generic/mcs_spinlock.h
 create mode 100644 include/linux/mcs_spinlock.h

-- 
1.7.11.7

[PATCH v9 1/6] MCS Lock: Barrier corrections

[Tim Chen]

From: Waiman Long <Waiman.Long@hp.com>

This patch corrects the way memory barriers are used in the MCS lock
with smp_load_acquire and smp_store_release fucnctions.  The previous
barriers could leak critical sections if mcs lock is used by itself.
It is not a problem when mcs lock is embedded in mutex but will be an
issue when the mcs_lock is used elsewhere.

The patch removes the incorrect barriers and put in correct
barriers with the pair of functions smp_load_acquire and smp_store_release.

Suggested-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 kernel/locking/mutex.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 4dd6e4c..fbbd2ed 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -136,9 +136,12 @@ void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
-	smp_wmb();
-	/* Wait until the lock holder passes the lock down */
-	while (!ACCESS_ONCE(node->locked))
+	/*
+	 * Wait until the lock holder passes the lock down.
+	 * Using smp_load_acquire() provides a memory barrier that
+	 * ensures subsequent operations happen after the lock is acquired.
+	 */
+	while (!(smp_load_acquire(&node->locked)))
 		arch_mutex_cpu_relax();
 }
 
@@ -156,8 +159,13 @@ static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
 		while (!(next = ACCESS_ONCE(node->next)))
 			arch_mutex_cpu_relax();
 	}
-	ACCESS_ONCE(next->locked) = 1;
-	smp_wmb();
+	/*
+	 * Pass lock to next waiter.
+	 * smp_store_release() provides a memory barrier to ensure
+	 * all operations in the critical section has been completed
+	 * before unlocking.
+	 */
+	smp_store_release(&next->locked, 1);
 }
 
 /*
-- 
1.7.11.7

[tip:core/locking] locking/mutexes/mcs: Correct barrier usage

[tip-bot for Waiman Long]

Commit-ID:  aff7385b5a16bca6b8d9243f01a9ea5a5b411e1d
Gitweb:     http://git.kernel.org/tip/aff7385b5a16bca6b8d9243f01a9ea5a5b411e1d
Author:     Waiman Long <Waiman.Long@hp.com>
AuthorDate: Tue, 21 Jan 2014 15:35:53 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Jan 2014 13:13:26 +0100

locking/mutexes/mcs: Correct barrier usage

This patch corrects the way memory barriers are used in the MCS lock
with smp_load_acquire and smp_store_release fucnctions.  The previous
barriers could leak critical sections if mcs lock is used by itself.
It is not a problem when mcs lock is embedded in mutex but will be an
issue when the mcs_lock is used elsewhere.

The patch removes the incorrect barriers and put in correct
barriers with the pair of functions smp_load_acquire and smp_store_release.

Suggested-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1390347353.3138.62.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/locking/mutex.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 4dd6e4c..fbbd2ed 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -136,9 +136,12 @@ void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
-	smp_wmb();
-	/* Wait until the lock holder passes the lock down */
-	while (!ACCESS_ONCE(node->locked))
+	/*
+	 * Wait until the lock holder passes the lock down.
+	 * Using smp_load_acquire() provides a memory barrier that
+	 * ensures subsequent operations happen after the lock is acquired.
+	 */
+	while (!(smp_load_acquire(&node->locked)))
 		arch_mutex_cpu_relax();
 }
 
@@ -156,8 +159,13 @@ static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
 		while (!(next = ACCESS_ONCE(node->next)))
 			arch_mutex_cpu_relax();
 	}
-	ACCESS_ONCE(next->locked) = 1;
-	smp_wmb();
+	/*
+	 * Pass lock to next waiter.
+	 * smp_store_release() provides a memory barrier to ensure
+	 * all operations in the critical section has been completed
+	 * before unlocking.
+	 */
+	smp_store_release(&next->locked, 1);
 }
 
 /*

[PATCH v9 2/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file

[Tim Chen]

We will need the MCS lock code for doing optimistic spinning for rwsem
and queued rwlock.  Extracting the MCS code from mutex.c and put into
its own file allow us to reuse this code easily.

We also inline mcs_spin_lock and mcs_spin_unlock functions
for better efficiency.

Note that using the smp_load_acquire/smp_store_release pair used in
mcs_lock and mcs_unlock is not sufficient to form a full memory barrier
across cpus for many architectures (except x86).  For applications that
absolutely need a full barrier across multiple cpus with mcs_unlock and
mcs_lock pair, smp_mb__after_unlock_lock() should be used after mcs_lock.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
---
 include/linux/mcs_spinlock.h | 77 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mutex.h        |  5 +--
 kernel/locking/mutex.c       | 68 ++++----------------------------------
 3 files changed, 87 insertions(+), 63 deletions(-)
 create mode 100644 include/linux/mcs_spinlock.h

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
new file mode 100644
index 0000000..9578ef8
--- /dev/null
+++ b/include/linux/mcs_spinlock.h
@@ -0,0 +1,77 @@
+/*
+ * MCS lock defines
+ *
+ * This file contains the main data structure and API definitions of MCS lock.
+ *
+ * The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock
+ * with the desirable properties of being fair, and with each cpu trying
+ * to acquire the lock spinning on a local variable.
+ * It avoids expensive cache bouncings that common test-and-set spin-lock
+ * implementations incur.
+ */
+#ifndef __LINUX_MCS_SPINLOCK_H
+#define __LINUX_MCS_SPINLOCK_H
+
+struct mcs_spinlock {
+	struct mcs_spinlock *next;
+	int locked; /* 1 if lock acquired */
+};
+
+/*
+ * Note: the smp_load_acquire/smp_store_release pair is not
+ * sufficient to form a full memory barrier across
+ * cpus for many architectures (except x86) for mcs_unlock and mcs_lock.
+ * For applications that need a full barrier across multiple cpus
+ * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
+ * used after mcs_lock.
+ */
+static inline
+void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *prev;
+
+	/* Init node */
+	node->locked = 0;
+	node->next   = NULL;
+
+	prev = xchg(lock, node);
+	if (likely(prev == NULL)) {
+		/* Lock acquired */
+		node->locked = 1;
+		return;
+	}
+	ACCESS_ONCE(prev->next) = node;
+	/*
+	 * Wait until the lock holder passes the lock down.
+	 * Using smp_load_acquire() provides a memory barrier that
+	 * ensures subsequent operations happen after the lock is acquired.
+	 */
+	while (!(smp_load_acquire(&node->locked)))
+		arch_mutex_cpu_relax();
+}
+
+static inline
+void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *next = ACCESS_ONCE(node->next);
+
+	if (likely(!next)) {
+		/*
+		 * Release the lock by setting it to NULL
+		 */
+		if (cmpxchg(lock, node, NULL) == node)
+			return;
+		/* Wait until the next pointer is set */
+		while (!(next = ACCESS_ONCE(node->next)))
+			arch_mutex_cpu_relax();
+	}
+	/*
+	 * Pass lock to next waiter.
+	 * smp_store_release() provides a memory barrier to ensure
+	 * all operations in the critical section has been completed
+	 * before unlocking.
+	 */
+	smp_store_release(&next->locked, 1);
+}
+
+#endif /* __LINUX_MCS_SPINLOCK_H */
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index d318193..c482e1d 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -46,6 +46,7 @@
  * - detects multi-task circular deadlocks and prints out all affected
  *   locks and tasks (and only those tasks)
  */
+struct mcs_spinlock;
 struct mutex {
 	/* 1: unlocked, 0: locked, negative: locked, possible waiters */
 	atomic_t		count;
@@ -55,7 +56,7 @@ struct mutex {
 	struct task_struct	*owner;
 #endif
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-	void			*spin_mlock;	/* Spinner MCS lock */
+	struct mcs_spinlock	*mcs_lock;	/* Spinner MCS lock */
 #endif
 #ifdef CONFIG_DEBUG_MUTEXES
 	const char 		*name;
@@ -179,4 +180,4 @@ extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
 # define arch_mutex_cpu_relax() cpu_relax()
 #endif
 
-#endif
+#endif /* __LINUX_MUTEX_H */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index fbbd2ed..45fe1b5 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -25,6 +25,7 @@
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
 #include <linux/debug_locks.h>
+#include <linux/mcs_spinlock.h>
 
 /*
  * In the DEBUG case we are using the "NULL fastpath" for mutexes,
@@ -52,7 +53,7 @@ __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
 	INIT_LIST_HEAD(&lock->wait_list);
 	mutex_clear_owner(lock);
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-	lock->spin_mlock = NULL;
+	lock->mcs_lock = NULL;
 #endif
 
 	debug_mutex_init(lock, name, key);
@@ -111,62 +112,7 @@ EXPORT_SYMBOL(mutex_lock);
  * more or less simultaneously, the spinners need to acquire a MCS lock
  * first before spinning on the owner field.
  *
- * We don't inline mspin_lock() so that perf can correctly account for the
- * time spent in this lock function.
  */
-struct mspin_node {
-	struct mspin_node *next ;
-	int		  locked;	/* 1 if lock acquired */
-};
-#define	MLOCK(mutex)	((struct mspin_node **)&((mutex)->spin_mlock))
-
-static noinline
-void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
-{
-	struct mspin_node *prev;
-
-	/* Init node */
-	node->locked = 0;
-	node->next   = NULL;
-
-	prev = xchg(lock, node);
-	if (likely(prev == NULL)) {
-		/* Lock acquired */
-		node->locked = 1;
-		return;
-	}
-	ACCESS_ONCE(prev->next) = node;
-	/*
-	 * Wait until the lock holder passes the lock down.
-	 * Using smp_load_acquire() provides a memory barrier that
-	 * ensures subsequent operations happen after the lock is acquired.
-	 */
-	while (!(smp_load_acquire(&node->locked)))
-		arch_mutex_cpu_relax();
-}
-
-static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
-{
-	struct mspin_node *next = ACCESS_ONCE(node->next);
-
-	if (likely(!next)) {
-		/*
-		 * Release the lock by setting it to NULL
-		 */
-		if (cmpxchg(lock, node, NULL) == node)
-			return;
-		/* Wait until the next pointer is set */
-		while (!(next = ACCESS_ONCE(node->next)))
-			arch_mutex_cpu_relax();
-	}
-	/*
-	 * Pass lock to next waiter.
-	 * smp_store_release() provides a memory barrier to ensure
-	 * all operations in the critical section has been completed
-	 * before unlocking.
-	 */
-	smp_store_release(&next->locked, 1);
-}
 
 /*
  * Mutex spinning code migrated from kernel/sched/core.c
@@ -456,7 +402,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 
 	for (;;) {
 		struct task_struct *owner;
-		struct mspin_node  node;
+		struct mcs_spinlock  node;
 
 		if (use_ww_ctx && ww_ctx->acquired > 0) {
 			struct ww_mutex *ww;
@@ -478,10 +424,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 		 * If there's an owner, wait for it to either
 		 * release the lock or go to sleep.
 		 */
-		mspin_lock(MLOCK(lock), &node);
+		mcs_spin_lock(&lock->mcs_lock, &node);
 		owner = ACCESS_ONCE(lock->owner);
 		if (owner && !mutex_spin_on_owner(lock, owner)) {
-			mspin_unlock(MLOCK(lock), &node);
+			mcs_spin_unlock(&lock->mcs_lock, &node);
 			goto slowpath;
 		}
 
@@ -496,11 +442,11 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 			}
 
 			mutex_set_owner(lock);
-			mspin_unlock(MLOCK(lock), &node);
+			mcs_spin_unlock(&lock->mcs_lock, &node);
 			preempt_enable();
 			return 0;
 		}
-		mspin_unlock(MLOCK(lock), &node);
+		mcs_spin_unlock(&lock->mcs_lock, &node);
 
 		/*
 		 * When there's no owner, we might have preempted between the
-- 
1.7.11.7

[tip:core/locking] locking/mutexes/mcs: Restructure the MCS lock defines and locking code into its own file

[tip-bot for Tim Chen]

Commit-ID:  e72246748ff006ab928bc774e276e6ef5542f9c5
Gitweb:     http://git.kernel.org/tip/e72246748ff006ab928bc774e276e6ef5542f9c5
Author:     Tim Chen <tim.c.chen@linux.intel.com>
AuthorDate: Tue, 21 Jan 2014 15:36:00 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Jan 2014 13:13:27 +0100

locking/mutexes/mcs: Restructure the MCS lock defines and locking code into its own file

We will need the MCS lock code for doing optimistic spinning for rwsem
and queued rwlock.  Extracting the MCS code from mutex.c and put into
its own file allow us to reuse this code easily.

We also inline mcs_spin_lock and mcs_spin_unlock functions
for better efficiency.

Note that using the smp_load_acquire/smp_store_release pair used in
mcs_lock and mcs_unlock is not sufficient to form a full memory barrier
across cpus for many architectures (except x86).  For applications that
absolutely need a full barrier across multiple cpus with mcs_unlock and
mcs_lock pair, smp_mb__after_unlock_lock() should be used after mcs_lock.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1390347360.3138.63.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/mcs_spinlock.h | 77 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mutex.h        |  5 +--
 kernel/locking/mutex.c       | 68 ++++----------------------------------
 3 files changed, 87 insertions(+), 63 deletions(-)

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
new file mode 100644
index 0000000..9578ef8
--- /dev/null
+++ b/include/linux/mcs_spinlock.h
@@ -0,0 +1,77 @@
+/*
+ * MCS lock defines
+ *
+ * This file contains the main data structure and API definitions of MCS lock.
+ *
+ * The MCS lock (proposed by Mellor-Crummey and Scott) is a simple spin-lock
+ * with the desirable properties of being fair, and with each cpu trying
+ * to acquire the lock spinning on a local variable.
+ * It avoids expensive cache bouncings that common test-and-set spin-lock
+ * implementations incur.
+ */
+#ifndef __LINUX_MCS_SPINLOCK_H
+#define __LINUX_MCS_SPINLOCK_H
+
+struct mcs_spinlock {
+	struct mcs_spinlock *next;
+	int locked; /* 1 if lock acquired */
+};
+
+/*
+ * Note: the smp_load_acquire/smp_store_release pair is not
+ * sufficient to form a full memory barrier across
+ * cpus for many architectures (except x86) for mcs_unlock and mcs_lock.
+ * For applications that need a full barrier across multiple cpus
+ * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
+ * used after mcs_lock.
+ */
+static inline
+void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *prev;
+
+	/* Init node */
+	node->locked = 0;
+	node->next   = NULL;
+
+	prev = xchg(lock, node);
+	if (likely(prev == NULL)) {
+		/* Lock acquired */
+		node->locked = 1;
+		return;
+	}
+	ACCESS_ONCE(prev->next) = node;
+	/*
+	 * Wait until the lock holder passes the lock down.
+	 * Using smp_load_acquire() provides a memory barrier that
+	 * ensures subsequent operations happen after the lock is acquired.
+	 */
+	while (!(smp_load_acquire(&node->locked)))
+		arch_mutex_cpu_relax();
+}
+
+static inline
+void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
+{
+	struct mcs_spinlock *next = ACCESS_ONCE(node->next);
+
+	if (likely(!next)) {
+		/*
+		 * Release the lock by setting it to NULL
+		 */
+		if (cmpxchg(lock, node, NULL) == node)
+			return;
+		/* Wait until the next pointer is set */
+		while (!(next = ACCESS_ONCE(node->next)))
+			arch_mutex_cpu_relax();
+	}
+	/*
+	 * Pass lock to next waiter.
+	 * smp_store_release() provides a memory barrier to ensure
+	 * all operations in the critical section has been completed
+	 * before unlocking.
+	 */
+	smp_store_release(&next->locked, 1);
+}
+
+#endif /* __LINUX_MCS_SPINLOCK_H */
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index d318193..c482e1d 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -46,6 +46,7 @@
  * - detects multi-task circular deadlocks and prints out all affected
  *   locks and tasks (and only those tasks)
  */
+struct mcs_spinlock;
 struct mutex {
 	/* 1: unlocked, 0: locked, negative: locked, possible waiters */
 	atomic_t		count;
@@ -55,7 +56,7 @@ struct mutex {
 	struct task_struct	*owner;
 #endif
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-	void			*spin_mlock;	/* Spinner MCS lock */
+	struct mcs_spinlock	*mcs_lock;	/* Spinner MCS lock */
 #endif
 #ifdef CONFIG_DEBUG_MUTEXES
 	const char 		*name;
@@ -179,4 +180,4 @@ extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
 # define arch_mutex_cpu_relax() cpu_relax()
 #endif
 
-#endif
+#endif /* __LINUX_MUTEX_H */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index fbbd2ed..45fe1b5 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -25,6 +25,7 @@
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
 #include <linux/debug_locks.h>
+#include <linux/mcs_spinlock.h>
 
 /*
  * In the DEBUG case we are using the "NULL fastpath" for mutexes,
@@ -52,7 +53,7 @@ __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
 	INIT_LIST_HEAD(&lock->wait_list);
 	mutex_clear_owner(lock);
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
-	lock->spin_mlock = NULL;
+	lock->mcs_lock = NULL;
 #endif
 
 	debug_mutex_init(lock, name, key);
@@ -111,62 +112,7 @@ EXPORT_SYMBOL(mutex_lock);
  * more or less simultaneously, the spinners need to acquire a MCS lock
  * first before spinning on the owner field.
  *
- * We don't inline mspin_lock() so that perf can correctly account for the
- * time spent in this lock function.
  */
-struct mspin_node {
-	struct mspin_node *next ;
-	int		  locked;	/* 1 if lock acquired */
-};
-#define	MLOCK(mutex)	((struct mspin_node **)&((mutex)->spin_mlock))
-
-static noinline
-void mspin_lock(struct mspin_node **lock, struct mspin_node *node)
-{
-	struct mspin_node *prev;
-
-	/* Init node */
-	node->locked = 0;
-	node->next   = NULL;
-
-	prev = xchg(lock, node);
-	if (likely(prev == NULL)) {
-		/* Lock acquired */
-		node->locked = 1;
-		return;
-	}
-	ACCESS_ONCE(prev->next) = node;
-	/*
-	 * Wait until the lock holder passes the lock down.
-	 * Using smp_load_acquire() provides a memory barrier that
-	 * ensures subsequent operations happen after the lock is acquired.
-	 */
-	while (!(smp_load_acquire(&node->locked)))
-		arch_mutex_cpu_relax();
-}
-
-static void mspin_unlock(struct mspin_node **lock, struct mspin_node *node)
-{
-	struct mspin_node *next = ACCESS_ONCE(node->next);
-
-	if (likely(!next)) {
-		/*
-		 * Release the lock by setting it to NULL
-		 */
-		if (cmpxchg(lock, node, NULL) == node)
-			return;
-		/* Wait until the next pointer is set */
-		while (!(next = ACCESS_ONCE(node->next)))
-			arch_mutex_cpu_relax();
-	}
-	/*
-	 * Pass lock to next waiter.
-	 * smp_store_release() provides a memory barrier to ensure
-	 * all operations in the critical section has been completed
-	 * before unlocking.
-	 */
-	smp_store_release(&next->locked, 1);
-}
 
 /*
  * Mutex spinning code migrated from kernel/sched/core.c
@@ -456,7 +402,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 
 	for (;;) {
 		struct task_struct *owner;
-		struct mspin_node  node;
+		struct mcs_spinlock  node;
 
 		if (use_ww_ctx && ww_ctx->acquired > 0) {
 			struct ww_mutex *ww;
@@ -478,10 +424,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 		 * If there's an owner, wait for it to either
 		 * release the lock or go to sleep.
 		 */
-		mspin_lock(MLOCK(lock), &node);
+		mcs_spin_lock(&lock->mcs_lock, &node);
 		owner = ACCESS_ONCE(lock->owner);
 		if (owner && !mutex_spin_on_owner(lock, owner)) {
-			mspin_unlock(MLOCK(lock), &node);
+			mcs_spin_unlock(&lock->mcs_lock, &node);
 			goto slowpath;
 		}
 
@@ -496,11 +442,11 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
 			}
 
 			mutex_set_owner(lock);
-			mspin_unlock(MLOCK(lock), &node);
+			mcs_spin_unlock(&lock->mcs_lock, &node);
 			preempt_enable();
 			return 0;
 		}
-		mspin_unlock(MLOCK(lock), &node);
+		mcs_spin_unlock(&lock->mcs_lock, &node);
 
 		/*
 		 * When there's no owner, we might have preempted between the

[PATCH v9 3/6] MCS Lock: Optimizations and extra comments

[Tim Chen]

From: Jason Low <jason.low2@hp.com>

Remove unnecessary operation to assign locked status to 1 if lock is
acquired without contention. Lock status will not be checked by lock
holder again once it is acquired and any lock
contenders will not be looking at the lock holder's lock status.

Make the cmpxchg(lock, node, NULL) == node check in mcs_spin_unlock()
likely() as it is likely that a race did not occur most of the time.

Also add in more comments describing how the local node is used in MCS locks.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 include/linux/mcs_spinlock.h | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index 9578ef8..143fa42 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -25,6 +25,17 @@ struct mcs_spinlock {
  * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
  * used after mcs_lock.
  */
+
+/*
+ * In order to acquire the lock, the caller should declare a local node and
+ * pass a reference of the node to this function in addition to the lock.
+ * If the lock has already been acquired, then this will proceed to spin
+ * on this node->locked until the previous lock holder sets the node->locked
+ * in mcs_spin_unlock().
+ *
+ * We don't inline mcs_spin_lock() so that perf can correctly account for the
+ * time spent in this lock function.
+ */
 static inline
 void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 {
@@ -36,8 +47,14 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 
 	prev = xchg(lock, node);
 	if (likely(prev == NULL)) {
-		/* Lock acquired */
-		node->locked = 1;
+		/*
+		 * Lock acquired, don't need to set node->locked to 1. Threads
+		 * only spin on its own node->locked value for lock acquisition.
+		 * However, since this thread can immediately acquire the lock
+		 * and does not proceed to spin on its own node->locked, this
+		 * value won't be used. If a debug mode is needed to
+		 * audit lock status, then set node->locked value here.
+		 */
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
@@ -50,6 +67,10 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		arch_mutex_cpu_relax();
 }
 
+/*
+ * Releases the lock. The caller should pass in the corresponding node that
+ * was used to acquire the lock.
+ */
 static inline
 void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 {
@@ -59,7 +80,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		/*
 		 * Release the lock by setting it to NULL
 		 */
-		if (cmpxchg(lock, node, NULL) == node)
+		if (likely(cmpxchg(lock, node, NULL) == node))
 			return;
 		/* Wait until the next pointer is set */
 		while (!(next = ACCESS_ONCE(node->next)))
-- 
1.7.11.7

[tip:core/locking] locking/mcs: Micro-optimize the MCS code, add extra comments

[tip-bot for Jason Low]

Commit-ID:  5faeb8adb956a5ad6579c4e309e8689943ad8294
Gitweb:     http://git.kernel.org/tip/5faeb8adb956a5ad6579c4e309e8689943ad8294
Author:     Jason Low <jason.low2@hp.com>
AuthorDate: Tue, 21 Jan 2014 15:36:05 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Jan 2014 13:13:28 +0100

locking/mcs: Micro-optimize the MCS code, add extra comments

Remove unnecessary operation to assign locked status to 1 if lock is
acquired without contention. Lock status will not be checked by lock
holder again once it is acquired and any lock
contenders will not be looking at the lock holder's lock status.

Make the cmpxchg(lock, node, NULL) == node check in mcs_spin_unlock()
likely() as it is likely that a race did not occur most of the time.

Also add in more comments describing how the local node is used in MCS locks.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1390347365.3138.64.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/mcs_spinlock.h | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index 9578ef8..143fa42 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -25,6 +25,17 @@ struct mcs_spinlock {
  * with mcs_unlock and mcs_lock pair, smp_mb__after_unlock_lock() should be
  * used after mcs_lock.
  */
+
+/*
+ * In order to acquire the lock, the caller should declare a local node and
+ * pass a reference of the node to this function in addition to the lock.
+ * If the lock has already been acquired, then this will proceed to spin
+ * on this node->locked until the previous lock holder sets the node->locked
+ * in mcs_spin_unlock().
+ *
+ * We don't inline mcs_spin_lock() so that perf can correctly account for the
+ * time spent in this lock function.
+ */
 static inline
 void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 {
@@ -36,8 +47,14 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 
 	prev = xchg(lock, node);
 	if (likely(prev == NULL)) {
-		/* Lock acquired */
-		node->locked = 1;
+		/*
+		 * Lock acquired, don't need to set node->locked to 1. Threads
+		 * only spin on its own node->locked value for lock acquisition.
+		 * However, since this thread can immediately acquire the lock
+		 * and does not proceed to spin on its own node->locked, this
+		 * value won't be used. If a debug mode is needed to
+		 * audit lock status, then set node->locked value here.
+		 */
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
@@ -50,6 +67,10 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		arch_mutex_cpu_relax();
 }
 
+/*
+ * Releases the lock. The caller should pass in the corresponding node that
+ * was used to acquire the lock.
+ */
 static inline
 void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 {
@@ -59,7 +80,7 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		/*
 		 * Release the lock by setting it to NULL
 		 */
-		if (cmpxchg(lock, node, NULL) == node)
+		if (likely(cmpxchg(lock, node, NULL) == node))
 			return;
 		/* Wait until the next pointer is set */
 		while (!(next = ACCESS_ONCE(node->next)))

[PATCH v9 4/6] MCS Lock: Allow architectures to hook in to contended paths

[Tim Chen]

From: Will Deacon <will.deacon@arm.com

When contended, architectures may be able to reduce the polling overhead
in ways which aren't expressible using a simple relax() primitive.

This patch allows architectures to hook into the mcs_{lock,unlock}
functions for the contended cases only.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 include/linux/mcs_spinlock.h | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index 143fa42..e9a4d74 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -17,6 +17,28 @@ struct mcs_spinlock {
 	int locked; /* 1 if lock acquired */
 };
 
+#ifndef arch_mcs_spin_lock_contended
+/*
+ * Using smp_load_acquire() provides a memory barrier that ensures
+ * subsequent operations happen after the lock is acquired.
+ */
+#define arch_mcs_spin_lock_contended(l)					\
+do {									\
+	while (!(smp_load_acquire(l)))					\
+		arch_mutex_cpu_relax();					\
+} while (0)
+#endif
+
+#ifndef arch_mcs_spin_unlock_contended
+/*
+ * smp_store_release() provides a memory barrier to ensure all
+ * operations in the critical section has been completed before
+ * unlocking.
+ */
+#define arch_mcs_spin_unlock_contended(l)				\
+	smp_store_release((l), 1)
+#endif
+
 /*
  * Note: the smp_load_acquire/smp_store_release pair is not
  * sufficient to form a full memory barrier across
@@ -58,13 +80,9 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
-	/*
-	 * Wait until the lock holder passes the lock down.
-	 * Using smp_load_acquire() provides a memory barrier that
-	 * ensures subsequent operations happen after the lock is acquired.
-	 */
-	while (!(smp_load_acquire(&node->locked)))
-		arch_mutex_cpu_relax();
+
+	/* Wait until the lock holder passes the lock down. */
+	arch_mcs_spin_lock_contended(&node->locked);
 }
 
 /*
@@ -86,13 +104,9 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		while (!(next = ACCESS_ONCE(node->next)))
 			arch_mutex_cpu_relax();
 	}
-	/*
-	 * Pass lock to next waiter.
-	 * smp_store_release() provides a memory barrier to ensure
-	 * all operations in the critical section has been completed
-	 * before unlocking.
-	 */
-	smp_store_release(&next->locked, 1);
+
+	/* Pass lock to next waiter. */
+	arch_mcs_spin_unlock_contended(&next->locked);
 }
 
 #endif /* __LINUX_MCS_SPINLOCK_H */
-- 
1.7.11.7

[tip:core/locking] locking/mcs: Allow architectures to hook in to contended paths

[tip-bot for Will Deacon]

Commit-ID:  e207552e64ea053a33e856828ad7915484911d06
Gitweb:     http://git.kernel.org/tip/e207552e64ea053a33e856828ad7915484911d06
Author:     Will Deacon <will.deacon@arm.com>
AuthorDate: Tue, 21 Jan 2014 15:36:10 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Jan 2014 13:13:28 +0100

locking/mcs: Allow architectures to hook in to contended paths

When contended, architectures may be able to reduce the polling overhead
in ways which aren't expressible using a simple relax() primitive.

This patch allows architectures to hook into the mcs_{lock,unlock}
functions for the contended cases only.

Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1390347370.3138.65.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/mcs_spinlock.h | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index 143fa42..e9a4d74 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -17,6 +17,28 @@ struct mcs_spinlock {
 	int locked; /* 1 if lock acquired */
 };
 
+#ifndef arch_mcs_spin_lock_contended
+/*
+ * Using smp_load_acquire() provides a memory barrier that ensures
+ * subsequent operations happen after the lock is acquired.
+ */
+#define arch_mcs_spin_lock_contended(l)					\
+do {									\
+	while (!(smp_load_acquire(l)))					\
+		arch_mutex_cpu_relax();					\
+} while (0)
+#endif
+
+#ifndef arch_mcs_spin_unlock_contended
+/*
+ * smp_store_release() provides a memory barrier to ensure all
+ * operations in the critical section has been completed before
+ * unlocking.
+ */
+#define arch_mcs_spin_unlock_contended(l)				\
+	smp_store_release((l), 1)
+#endif
+
 /*
  * Note: the smp_load_acquire/smp_store_release pair is not
  * sufficient to form a full memory barrier across
@@ -58,13 +80,9 @@ void mcs_spin_lock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		return;
 	}
 	ACCESS_ONCE(prev->next) = node;
-	/*
-	 * Wait until the lock holder passes the lock down.
-	 * Using smp_load_acquire() provides a memory barrier that
-	 * ensures subsequent operations happen after the lock is acquired.
-	 */
-	while (!(smp_load_acquire(&node->locked)))
-		arch_mutex_cpu_relax();
+
+	/* Wait until the lock holder passes the lock down. */
+	arch_mcs_spin_lock_contended(&node->locked);
 }
 
 /*
@@ -86,13 +104,9 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
 		while (!(next = ACCESS_ONCE(node->next)))
 			arch_mutex_cpu_relax();
 	}
-	/*
-	 * Pass lock to next waiter.
-	 * smp_store_release() provides a memory barrier to ensure
-	 * all operations in the critical section has been completed
-	 * before unlocking.
-	 */
-	smp_store_release(&next->locked, 1);
+
+	/* Pass lock to next waiter. */
+	arch_mcs_spin_unlock_contended(&next->locked);
 }
 
 #endif /* __LINUX_MCS_SPINLOCK_H */

[PATCH v9 5/6] MCS Lock: Order the header files in Kbuild of each architecture in alphabetical order

[Tim Chen]

From: Peter Zijlstra <peterz@infradead.org>

We perform a clean up of the Kbuid files in each architecture.
We order the files in each Kbuild in alphabetical order
by running the below script on each Kbuild file:

gawk '/^generic-y/ {
        i = 3;
        do {
                for (; i<=NF; i++) {
                        if ($i == "\\") {
                                getline;
                                i=1;
                                continue;
                        }
                        if ($i != "")
                                hdr[$i] = $i;
                }
                break;
        } while (1);
        next;
}
END {
        n = asort(hdr);
        for (i=1; i<=n; i++)
                print "generic-y += " hdr[i];
}'

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 arch/alpha/include/asm/Kbuild      |  4 ++--
 arch/arc/include/asm/Kbuild        |  6 +++---
 arch/arm/include/asm/Kbuild        |  2 +-
 arch/arm64/include/asm/Kbuild      |  4 ++--
 arch/avr32/include/asm/Kbuild      | 38 +++++++++++++++++++-------------------
 arch/blackfin/include/asm/Kbuild   |  4 ++--
 arch/c6x/include/asm/Kbuild        |  2 +-
 arch/cris/include/asm/Kbuild       |  2 +-
 arch/frv/include/asm/Kbuild        |  2 +-
 arch/hexagon/include/asm/Kbuild    |  6 +++---
 arch/ia64/include/asm/Kbuild       |  4 ++--
 arch/m32r/include/asm/Kbuild       |  2 +-
 arch/m68k/include/asm/Kbuild       |  4 ++--
 arch/metag/include/asm/Kbuild      |  2 +-
 arch/microblaze/include/asm/Kbuild |  4 ++--
 arch/mips/include/asm/Kbuild       |  2 +-
 arch/mn10300/include/asm/Kbuild    |  2 +-
 arch/openrisc/include/asm/Kbuild   |  8 ++++----
 arch/parisc/include/asm/Kbuild     | 26 +++++++++++++++++++++-----
 arch/powerpc/include/asm/Kbuild    |  4 ++--
 arch/s390/include/asm/Kbuild       |  2 +-
 arch/score/include/asm/Kbuild      |  2 +-
 arch/sh/include/asm/Kbuild         |  6 +++---
 arch/sparc/include/asm/Kbuild      |  8 ++++----
 arch/tile/include/asm/Kbuild       |  2 +-
 arch/um/include/asm/Kbuild         | 29 ++++++++++++++++++++++++-----
 arch/unicore32/include/asm/Kbuild  |  2 +-
 arch/xtensa/include/asm/Kbuild     |  2 +-
 28 files changed, 108 insertions(+), 73 deletions(-)

diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index f01fb50..532356b 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -1,6 +1,6 @@
 
-generic-y += clkdev.h
 
+generic-y += clkdev.h
 generic-y += exec.h
-generic-y += trace_clock.h
 generic-y += preempt.h
+generic-y += trace_clock.h
diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 9ae21c1..4348dbc 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -1,15 +1,15 @@
 generic-y += auxvec.h
 generic-y += barrier.h
-generic-y += bugs.h
 generic-y += bitsperlong.h
+generic-y += bugs.h
 generic-y += clkdev.h
 generic-y += cputime.h
 generic-y += device.h
 generic-y += div64.h
 generic-y += emergency-restart.h
 generic-y += errno.h
-generic-y += fcntl.h
 generic-y += fb.h
+generic-y += fcntl.h
 generic-y += ftrace.h
 generic-y += hardirq.h
 generic-y += hw_irq.h
@@ -29,6 +29,7 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sembuf.h
@@ -47,4 +48,3 @@ generic-y += ucontext.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index c38b58c..8f37076 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -17,6 +17,7 @@ generic-y += msgbuf.h
 generic-y += param.h
 generic-y += parport.h
 generic-y += poll.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += sections.h
 generic-y += segment.h
@@ -33,4 +34,3 @@ generic-y += termios.h
 generic-y += timex.h
 generic-y += trace_clock.h
 generic-y += unaligned.h
-generic-y += preempt.h
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index 519f89f..a14534d 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -29,6 +29,7 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sections.h
@@ -39,8 +40,8 @@ generic-y += shmbuf.h
 generic-y += sizes.h
 generic-y += socket.h
 generic-y += sockios.h
-generic-y += switch_to.h
 generic-y += swab.h
+generic-y += switch_to.h
 generic-y += termbits.h
 generic-y += termios.h
 generic-y += topology.h
@@ -50,4 +51,3 @@ generic-y += unaligned.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/avr32/include/asm/Kbuild b/arch/avr32/include/asm/Kbuild
index 658001b..d831429 100644
--- a/arch/avr32/include/asm/Kbuild
+++ b/arch/avr32/include/asm/Kbuild
@@ -1,20 +1,20 @@
 
-generic-y	+= clkdev.h
-generic-y       += cputime.h
-generic-y       += delay.h
-generic-y       += device.h
-generic-y       += div64.h
-generic-y       += emergency-restart.h
-generic-y	+= exec.h
-generic-y       += futex.h
-generic-y	+= preempt.h
-generic-y       += irq_regs.h
-generic-y	+= param.h
-generic-y       += local.h
-generic-y       += local64.h
-generic-y       += percpu.h
-generic-y       += scatterlist.h
-generic-y       += sections.h
-generic-y       += topology.h
-generic-y	+= trace_clock.h
-generic-y       += xor.h
+generic-y += clkdev.h
+generic-y += cputime.h
+generic-y += delay.h
+generic-y += device.h
+generic-y += div64.h
+generic-y += emergency-restart.h
+generic-y += exec.h
+generic-y += futex.h
+generic-y += irq_regs.h
+generic-y += local.h
+generic-y += local64.h
+generic-y += param.h
+generic-y += percpu.h
+generic-y += preempt.h
+generic-y += scatterlist.h
+generic-y += sections.h
+generic-y += topology.h
+generic-y += trace_clock.h
+generic-y += xor.h
diff --git a/arch/blackfin/include/asm/Kbuild b/arch/blackfin/include/asm/Kbuild
index f2b4347..37b9282 100644
--- a/arch/blackfin/include/asm/Kbuild
+++ b/arch/blackfin/include/asm/Kbuild
@@ -17,14 +17,15 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += kvm_para.h
-generic-y += local64.h
 generic-y += local.h
+generic-y += local64.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += param.h
 generic-y += percpu.h
 generic-y += pgalloc.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sembuf.h
@@ -44,4 +45,3 @@ generic-y += ucontext.h
 generic-y += unaligned.h
 generic-y += user.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/c6x/include/asm/Kbuild b/arch/c6x/include/asm/Kbuild
index fc0b3c3..4b3f516 100644
--- a/arch/c6x/include/asm/Kbuild
+++ b/arch/c6x/include/asm/Kbuild
@@ -34,6 +34,7 @@ generic-y += percpu.h
 generic-y += pgalloc.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += segment.h
@@ -56,4 +57,3 @@ generic-y += ucontext.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/cris/include/asm/Kbuild b/arch/cris/include/asm/Kbuild
index 199b1a9..85c090d 100644
--- a/arch/cris/include/asm/Kbuild
+++ b/arch/cris/include/asm/Kbuild
@@ -9,7 +9,7 @@ generic-y += exec.h
 generic-y += kvm_para.h
 generic-y += linkage.h
 generic-y += module.h
+generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/frv/include/asm/Kbuild b/arch/frv/include/asm/Kbuild
index 74742dc..695246e 100644
--- a/arch/frv/include/asm/Kbuild
+++ b/arch/frv/include/asm/Kbuild
@@ -1,5 +1,5 @@
 
 generic-y += clkdev.h
 generic-y += exec.h
-generic-y += trace_clock.h
 generic-y += preempt.h
+generic-y += trace_clock.h
diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild
index ada843c..17f3996 100644
--- a/arch/hexagon/include/asm/Kbuild
+++ b/arch/hexagon/include/asm/Kbuild
@@ -24,14 +24,15 @@ generic-y += ipcbuf.h
 generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
-generic-y += local64.h
 generic-y += local.h
+generic-y += local64.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += pci.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += rwsem.h
 generic-y += scatterlist.h
@@ -44,8 +45,8 @@ generic-y += siginfo.h
 generic-y += sizes.h
 generic-y += socket.h
 generic-y += sockios.h
-generic-y += statfs.h
 generic-y += stat.h
+generic-y += statfs.h
 generic-y += termbits.h
 generic-y += termios.h
 generic-y += topology.h
@@ -54,4 +55,3 @@ generic-y += types.h
 generic-y += ucontext.h
 generic-y += unaligned.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild
index f93ee08..6f1de3b 100644
--- a/arch/ia64/include/asm/Kbuild
+++ b/arch/ia64/include/asm/Kbuild
@@ -2,6 +2,6 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += kvm_para.h
-generic-y += trace_clock.h
 generic-y += preempt.h
-generic-y += vtime.h
\ No newline at end of file
+generic-y += trace_clock.h
+generic-y += vtime.h
diff --git a/arch/m32r/include/asm/Kbuild b/arch/m32r/include/asm/Kbuild
index 2b58c5f..5cfbdd4 100644
--- a/arch/m32r/include/asm/Kbuild
+++ b/arch/m32r/include/asm/Kbuild
@@ -2,5 +2,5 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += module.h
-generic-y += trace_clock.h
 generic-y += preempt.h
+generic-y += trace_clock.h
diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild
index a5d27f2..c690a6f 100644
--- a/arch/m68k/include/asm/Kbuild
+++ b/arch/m68k/include/asm/Kbuild
@@ -13,11 +13,12 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += kvm_para.h
-generic-y += local64.h
 generic-y += local.h
+generic-y += local64.h
 generic-y += mman.h
 generic-y += mutex.h
 generic-y += percpu.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sections.h
@@ -31,4 +32,3 @@ generic-y += trace_clock.h
 generic-y += types.h
 generic-y += word-at-a-time.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/metag/include/asm/Kbuild b/arch/metag/include/asm/Kbuild
index 84d0c1d..3fc4a2e 100644
--- a/arch/metag/include/asm/Kbuild
+++ b/arch/metag/include/asm/Kbuild
@@ -30,6 +30,7 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += scatterlist.h
 generic-y += sections.h
 generic-y += sembuf.h
@@ -52,4 +53,3 @@ generic-y += unaligned.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index a824265..88968fa 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -2,6 +2,6 @@
 generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
-generic-y += trace_clock.h
-generic-y += syscalls.h
 generic-y += preempt.h
+generic-y += syscalls.h
+generic-y += trace_clock.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 1acbb8b..ef38961 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -6,11 +6,11 @@ generic-y += local64.h
 generic-y += mutex.h
 generic-y += parport.h
 generic-y += percpu.h
+generic-y += preempt.h
 generic-y += scatterlist.h
 generic-y += sections.h
 generic-y += segment.h
 generic-y += serial.h
 generic-y += trace_clock.h
-generic-y += preempt.h
 generic-y += ucontext.h
 generic-y += xor.h
diff --git a/arch/mn10300/include/asm/Kbuild b/arch/mn10300/include/asm/Kbuild
index 032143e..6fb781f 100644
--- a/arch/mn10300/include/asm/Kbuild
+++ b/arch/mn10300/include/asm/Kbuild
@@ -2,5 +2,5 @@
 generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
-generic-y += trace_clock.h
 generic-y += preempt.h
+generic-y += trace_clock.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index da1951a..32b5562 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -10,8 +10,8 @@ generic-y += bugs.h
 generic-y += cacheflush.h
 generic-y += checksum.h
 generic-y += clkdev.h
-generic-y += cmpxchg.h
 generic-y += cmpxchg-local.h
+generic-y += cmpxchg.h
 generic-y += cputime.h
 generic-y += current.h
 generic-y += device.h
@@ -41,6 +41,7 @@ generic-y += pci.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sections.h
@@ -53,11 +54,11 @@ generic-y += siginfo.h
 generic-y += signal.h
 generic-y += socket.h
 generic-y += sockios.h
-generic-y += statfs.h
 generic-y += stat.h
+generic-y += statfs.h
 generic-y += string.h
-generic-y += switch_to.h
 generic-y += swab.h
+generic-y += switch_to.h
 generic-y += termbits.h
 generic-y += termios.h
 generic-y += topology.h
@@ -68,4 +69,3 @@ generic-y += user.h
 generic-y += vga.h
 generic-y += word-at-a-time.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild
index 34b0be4..bb0d9ebb 100644
--- a/arch/parisc/include/asm/Kbuild
+++ b/arch/parisc/include/asm/Kbuild
@@ -1,8 +1,24 @@
 
+generic-y += auxvec.h
 generic-y += barrier.h
-generic-y += word-at-a-time.h auxvec.h user.h cputime.h emergency-restart.h \
-	  segment.h topology.h vga.h device.h percpu.h hw_irq.h mutex.h \
-	  div64.h irq_regs.h kdebug.h kvm_para.h local64.h local.h param.h \
-	  poll.h xor.h clkdev.h exec.h
-generic-y += trace_clock.h
+generic-y += clkdev.h
+generic-y += cputime.h
+generic-y += device.h
+generic-y += emergency-restart.h
+generic-y += exec.h
+generic-y += hw_irq.h
+generic-y += irq_regs.h
+generic-y += kdebug.h
+generic-y += kvm_para.h
+generic-y += local.h
+generic-y += local64.h
+generic-y += mutex.h
+generic-y += param.h
+generic-y += percpu.h
 generic-y += preempt.h
+generic-y += topology.h
+generic-y += trace_clock.h
+generic-y += user.h
+generic-y += vga.h
+generic-y += word-at-a-time.h
+generic-y += xor.h
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index d8f9d2f..8b19a80 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -1,6 +1,6 @@
 
 generic-y += clkdev.h
+generic-y += preempt.h
 generic-y += rwsem.h
 generic-y += trace_clock.h
-generic-y += preempt.h
-generic-y += vtime.h
\ No newline at end of file
+generic-y += vtime.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 7a5288f..6bd5f27 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -1,5 +1,5 @@
 

 generic-y += clkdev.h
-generic-y += trace_clock.h
 generic-y += preempt.h
+generic-y += trace_clock.h
diff --git a/arch/score/include/asm/Kbuild b/arch/score/include/asm/Kbuild
index fe7471e..064b55f 100644
--- a/arch/score/include/asm/Kbuild
+++ b/arch/score/include/asm/Kbuild
@@ -3,6 +3,6 @@ header-y +=
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index 231efbb..8856e73 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -14,12 +14,13 @@ generic-y += irq_regs.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mman.h
+generic-y += msgbuf.h
 generic-y += param.h
 generic-y += parport.h
 generic-y += percpu.h
 generic-y += poll.h
-generic-y += mman.h
-generic-y += msgbuf.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sembuf.h
@@ -34,4 +35,3 @@ generic-y += termios.h
 generic-y += trace_clock.h
 generic-y += ucontext.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index bf39066..3e78fda 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -6,14 +6,14 @@ generic-y += cputime.h
 generic-y += div64.h
 generic-y += emergency-restart.h
 generic-y += exec.h
-generic-y += linkage.h
-generic-y += local64.h
-generic-y += mutex.h
 generic-y += irq_regs.h
+generic-y += linkage.h
 generic-y += local.h
+generic-y += local64.h
 generic-y += module.h
+generic-y += mutex.h
+generic-y += preempt.h
 generic-y += serial.h
 generic-y += trace_clock.h
 generic-y += types.h
 generic-y += word-at-a-time.h
-generic-y += preempt.h
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index 22f3bd1..948549c 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/arch/tile/include/asm/Kbuild
@@ -24,6 +24,7 @@ generic-y += param.h
 generic-y += parport.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sembuf.h
@@ -38,4 +39,3 @@ generic-y += termios.h
 generic-y += trace_clock.h
 generic-y += types.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index fdde187..1cfae1f 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -1,6 +1,25 @@
-generic-y += bug.h cputime.h device.h emergency-restart.h futex.h hardirq.h
-generic-y += hw_irq.h irq_regs.h kdebug.h percpu.h sections.h topology.h xor.h
-generic-y += ftrace.h pci.h io.h param.h delay.h mutex.h current.h exec.h
-generic-y += switch_to.h clkdev.h
-generic-y += trace_clock.h
+generic-y += bug.h
+generic-y += clkdev.h
+generic-y += cputime.h
+generic-y += current.h
+generic-y += delay.h
+generic-y += device.h
+generic-y += emergency-restart.h
+generic-y += exec.h
+generic-y += ftrace.h
+generic-y += futex.h
+generic-y += hardirq.h
+generic-y += hw_irq.h
+generic-y += io.h
+generic-y += irq_regs.h
+generic-y += kdebug.h
+generic-y += mutex.h
+generic-y += param.h
+generic-y += pci.h
+generic-y += percpu.h
 generic-y += preempt.h
+generic-y += sections.h
+generic-y += switch_to.h
+generic-y += topology.h
+generic-y += trace_clock.h
+generic-y += xor.h
diff --git a/arch/unicore32/include/asm/Kbuild b/arch/unicore32/include/asm/Kbuild
index 00045cb..a61f73a 100644
--- a/arch/unicore32/include/asm/Kbuild
+++ b/arch/unicore32/include/asm/Kbuild
@@ -32,6 +32,7 @@ generic-y += parport.h
 generic-y += percpu.h
 generic-y += poll.h
 generic-y += posix_types.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sections.h
@@ -60,4 +61,3 @@ generic-y += unaligned.h
 generic-y += user.h
 generic-y += vga.h
 generic-y += xor.h
-generic-y += preempt.h
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index 228d6ae..68da9d4 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -19,6 +19,7 @@ generic-y += linkage.h
 generic-y += local.h
 generic-y += local64.h
 generic-y += percpu.h
+generic-y += preempt.h
 generic-y += resource.h
 generic-y += scatterlist.h
 generic-y += sections.h
@@ -28,4 +29,3 @@ generic-y += termios.h
 generic-y += topology.h
 generic-y += trace_clock.h
 generic-y += xor.h
-generic-y += preempt.h
-- 
1.7.11.7

[PATCH v9 6/6] MCS Lock: Allow architecture specific asm files to be used for contended case

[Tim Chen]

From: Peter Zijlstra <peterz@infradead.org>

This patch allows each architecture to add its specific assembly optimized
arch_mcs_spin_lock_contended and arch_mcs_spinlock_uncontended for
MCS lock and unlock functions.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
---
 arch/alpha/include/asm/Kbuild      |  1 +
 arch/arc/include/asm/Kbuild        |  1 +
 arch/arm/include/asm/Kbuild        |  1 +
 arch/arm64/include/asm/Kbuild      |  1 +
 arch/avr32/include/asm/Kbuild      |  1 +
 arch/blackfin/include/asm/Kbuild   |  1 +
 arch/c6x/include/asm/Kbuild        |  1 +
 arch/cris/include/asm/Kbuild       |  1 +
 arch/frv/include/asm/Kbuild        |  1 +
 arch/hexagon/include/asm/Kbuild    |  1 +
 arch/ia64/include/asm/Kbuild       |  1 +
 arch/m32r/include/asm/Kbuild       |  1 +
 arch/m68k/include/asm/Kbuild       |  1 +
 arch/metag/include/asm/Kbuild      |  1 +
 arch/microblaze/include/asm/Kbuild |  1 +
 arch/mips/include/asm/Kbuild       |  1 +
 arch/mn10300/include/asm/Kbuild    |  1 +
 arch/openrisc/include/asm/Kbuild   |  1 +
 arch/parisc/include/asm/Kbuild     |  1 +
 arch/powerpc/include/asm/Kbuild    |  4 +++-
 arch/s390/include/asm/Kbuild       |  1 +
 arch/score/include/asm/Kbuild      |  1 +
 arch/sh/include/asm/Kbuild         |  1 +
 arch/sparc/include/asm/Kbuild      |  1 +
 arch/tile/include/asm/Kbuild       |  1 +
 arch/um/include/asm/Kbuild         |  1 +
 arch/unicore32/include/asm/Kbuild  |  1 +
 arch/x86/include/asm/Kbuild        |  1 +
 arch/xtensa/include/asm/Kbuild     |  1 +
 include/asm-generic/mcs_spinlock.h | 13 +++++++++++++
 include/linux/mcs_spinlock.h       |  2 ++
 31 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 include/asm-generic/mcs_spinlock.h

diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index 532356b..a8a45e1 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -2,5 +2,6 @@
 
 generic-y += clkdev.h
 generic-y += exec.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 4348dbc..58fe4b5 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -21,6 +21,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += param.h
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index 8f37076..3df7d62 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -13,6 +13,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += param.h
 generic-y += parport.h
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index a14534d..3b99d2b 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -22,6 +22,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
diff --git a/arch/avr32/include/asm/Kbuild b/arch/avr32/include/asm/Kbuild
index d831429..29cb2c6 100644
--- a/arch/avr32/include/asm/Kbuild
+++ b/arch/avr32/include/asm/Kbuild
@@ -10,6 +10,7 @@ generic-y += futex.h
 generic-y += irq_regs.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += param.h
 generic-y += percpu.h
 generic-y += preempt.h
diff --git a/arch/blackfin/include/asm/Kbuild b/arch/blackfin/include/asm/Kbuild
index 37b9282..ebaccbb 100644
--- a/arch/blackfin/include/asm/Kbuild
+++ b/arch/blackfin/include/asm/Kbuild
@@ -19,6 +19,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
diff --git a/arch/c6x/include/asm/Kbuild b/arch/c6x/include/asm/Kbuild
index 4b3f516..d09762e 100644
--- a/arch/c6x/include/asm/Kbuild
+++ b/arch/c6x/include/asm/Kbuild
@@ -24,6 +24,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += mmu.h
 generic-y += mmu_context.h
diff --git a/arch/cris/include/asm/Kbuild b/arch/cris/include/asm/Kbuild
index 85c090d..d8e20e9 100644
--- a/arch/cris/include/asm/Kbuild
+++ b/arch/cris/include/asm/Kbuild
@@ -8,6 +8,7 @@ generic-y += clkdev.h
 generic-y += exec.h
 generic-y += kvm_para.h
 generic-y += linkage.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/frv/include/asm/Kbuild b/arch/frv/include/asm/Kbuild
index 695246e..5e1442b 100644
--- a/arch/frv/include/asm/Kbuild
+++ b/arch/frv/include/asm/Kbuild
@@ -1,5 +1,6 @@
 
 generic-y += clkdev.h
 generic-y += exec.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild
index 17f3996..55888ca 100644
--- a/arch/hexagon/include/asm/Kbuild
+++ b/arch/hexagon/include/asm/Kbuild
@@ -26,6 +26,7 @@ generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += pci.h
diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild
index 6f1de3b..cf1f005 100644
--- a/arch/ia64/include/asm/Kbuild
+++ b/arch/ia64/include/asm/Kbuild
@@ -2,6 +2,7 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += kvm_para.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += vtime.h
diff --git a/arch/m32r/include/asm/Kbuild b/arch/m32r/include/asm/Kbuild
index 5cfbdd4..e26e8dd 100644
--- a/arch/m32r/include/asm/Kbuild
+++ b/arch/m32r/include/asm/Kbuild
@@ -1,6 +1,7 @@
 
 generic-y += clkdev.h
 generic-y += exec.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild
index c690a6f..d9b0785 100644
--- a/arch/m68k/include/asm/Kbuild
+++ b/arch/m68k/include/asm/Kbuild
@@ -15,6 +15,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += mutex.h
 generic-y += percpu.h
diff --git a/arch/metag/include/asm/Kbuild b/arch/metag/include/asm/Kbuild
index 3fc4a2e..eb6d376 100644
--- a/arch/metag/include/asm/Kbuild
+++ b/arch/metag/include/asm/Kbuild
@@ -23,6 +23,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += param.h
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index 88968fa..3088588 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -2,6 +2,7 @@
 generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += syscalls.h
 generic-y += trace_clock.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index ef38961..8aa9b1b 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -3,6 +3,7 @@ generic-y += cputime.h
 generic-y += current.h
 generic-y += emergency-restart.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += parport.h
 generic-y += percpu.h
diff --git a/arch/mn10300/include/asm/Kbuild b/arch/mn10300/include/asm/Kbuild
index 6fb781f..97abbe7 100644
--- a/arch/mn10300/include/asm/Kbuild
+++ b/arch/mn10300/include/asm/Kbuild
@@ -2,5 +2,6 @@
 generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index 32b5562..6bf2601 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -34,6 +34,7 @@ generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += module.h
 generic-y += msgbuf.h
diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild
index bb0d9ebb..fa6065d 100644
--- a/arch/parisc/include/asm/Kbuild
+++ b/arch/parisc/include/asm/Kbuild
@@ -12,6 +12,7 @@ generic-y += kdebug.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += param.h
 generic-y += percpu.h
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index 8b19a80..24027ce 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -1,6 +1,8 @@
 
+generic-y += +=
 generic-y += clkdev.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += rwsem.h
 generic-y += trace_clock.h
-generic-y += vtime.h
+generic-y += vtime.hgeneric-y
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 6bd5f27..52bb0ba 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -1,5 +1,6 @@
 

 generic-y += clkdev.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/score/include/asm/Kbuild b/arch/score/include/asm/Kbuild
index 064b55f..fc22db4 100644
--- a/arch/score/include/asm/Kbuild
+++ b/arch/score/include/asm/Kbuild
@@ -3,6 +3,7 @@ header-y +=
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += xor.h
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index 8856e73..d5baf96 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -14,6 +14,7 @@ generic-y += irq_regs.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += param.h
diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index 3e78fda..793dbb0 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -10,6 +10,7 @@ generic-y += irq_regs.h
 generic-y += linkage.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += mutex.h
 generic-y += preempt.h
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index 948549c..f5433e0 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/arch/tile/include/asm/Kbuild
@@ -18,6 +18,7 @@ generic-y += ipcbuf.h
 generic-y += irq_regs.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += param.h
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 1cfae1f..82aed2d 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -13,6 +13,7 @@ generic-y += hw_irq.h
 generic-y += io.h
 generic-y += irq_regs.h
 generic-y += kdebug.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += param.h
 generic-y += pci.h
diff --git a/arch/unicore32/include/asm/Kbuild b/arch/unicore32/include/asm/Kbuild
index a61f73a..9de88a5 100644
--- a/arch/unicore32/include/asm/Kbuild
+++ b/arch/unicore32/include/asm/Kbuild
@@ -24,6 +24,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += module.h
 generic-y += msgbuf.h
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 7f66985..a8fee07 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -5,3 +5,4 @@ genhdr-y += unistd_64.h
 genhdr-y += unistd_x32.h
 
 generic-y += clkdev.h
+generic-y += mcs_spinlock.h
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index 68da9d4..1c8455c 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -18,6 +18,7 @@ generic-y += kvm_para.h
 generic-y += linkage.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += resource.h
diff --git a/include/asm-generic/mcs_spinlock.h b/include/asm-generic/mcs_spinlock.h
new file mode 100644
index 0000000..10cd4ff
--- /dev/null
+++ b/include/asm-generic/mcs_spinlock.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_MCS_SPINLOCK_H
+#define __ASM_MCS_SPINLOCK_H
+
+/*
+ * Architectures can define their own:
+ *
+ *   arch_mcs_spin_lock_contended(l)
+ *   arch_mcs_spin_unlock_contended(l)
+ *
+ * See kernel/locking/mcs_spinlock.c.
+ */
+
+#endif /* __ASM_MCS_SPINLOCK_H */
diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index e9a4d74..f2a5c63 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -12,6 +12,8 @@
 #ifndef __LINUX_MCS_SPINLOCK_H
 #define __LINUX_MCS_SPINLOCK_H
 
+#include <asm/mcs_spinlock.h>
+
 struct mcs_spinlock {
 	struct mcs_spinlock *next;
 	int locked; /* 1 if lock acquired */
-- 
1.7.11.7

Re: [PATCH v9 6/6] MCS Lock: Allow architecture specific asm files to be used for contended case

[Peter Zijlstra]

On Tue, Jan 21, 2014 at 03:36:22PM -0800, Tim Chen wrote:
> diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
> index 8b19a80..24027ce 100644
> --- a/arch/powerpc/include/asm/Kbuild
> +++ b/arch/powerpc/include/asm/Kbuild
> @@ -1,6 +1,8 @@
>  
> +generic-y += +=
>  generic-y += clkdev.h
> +generic-y += mcs_spinlock.h
>  generic-y += preempt.h
>  generic-y += rwsem.h
>  generic-y += trace_clock.h
> -generic-y += vtime.h
> +generic-y += vtime.hgeneric-y

Something went funny there, fixed it.

Re: [PATCH v9 6/6] MCS Lock: Allow architecture specific asm files to be used for contended case

[Tim Chen]

On Wed, 2014-01-22 at 19:35 +0100, Peter Zijlstra wrote:
> On Tue, Jan 21, 2014 at 03:36:22PM -0800, Tim Chen wrote:
> > diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
> > index 8b19a80..24027ce 100644
> > --- a/arch/powerpc/include/asm/Kbuild
> > +++ b/arch/powerpc/include/asm/Kbuild
> > @@ -1,6 +1,8 @@
> >  
> > +generic-y += +=
> >  generic-y += clkdev.h
> > +generic-y += mcs_spinlock.h
> >  generic-y += preempt.h
> >  generic-y += rwsem.h
> >  generic-y += trace_clock.h
> > -generic-y += vtime.h
> > +generic-y += vtime.hgeneric-y
> 
> Something went funny there, fixed it.

Thanks for fixing it.  I assume Peter you have picked up
the patch series and merged them?

Tim

Re: [PATCH v9 6/6] MCS Lock: Allow architecture specific asm files to be used for contended case

[Peter Zijlstra]

On Fri, Jan 24, 2014 at 09:03:49AM -0800, Tim Chen wrote:
> On Wed, 2014-01-22 at 19:35 +0100, Peter Zijlstra wrote:
> > On Tue, Jan 21, 2014 at 03:36:22PM -0800, Tim Chen wrote:
> > > diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
> > > index 8b19a80..24027ce 100644
> > > --- a/arch/powerpc/include/asm/Kbuild
> > > +++ b/arch/powerpc/include/asm/Kbuild
> > > @@ -1,6 +1,8 @@
> > >  
> > > +generic-y += +=
> > >  generic-y += clkdev.h
> > > +generic-y += mcs_spinlock.h
> > >  generic-y += preempt.h
> > >  generic-y += rwsem.h
> > >  generic-y += trace_clock.h
> > > -generic-y += vtime.h
> > > +generic-y += vtime.hgeneric-y
> > 
> > Something went funny there, fixed it.
> 
> Thanks for fixing it.  I assume Peter you have picked up
> the patch series and merged them?

I have picked up, Ingo generally doesn't merge new patches until after
-rc1 closes though, with the obvious exception to 'urgent' patches that
fix problems stemming from the merge window.

[tip:core/locking] locking/mcs: Allow architecture specific asm files to be used for contended case

[tip-bot for Tim Chen]

Commit-ID:  ddf1d169c0a489d498c1799a7043904a43b0c159
Gitweb:     http://git.kernel.org/tip/ddf1d169c0a489d498c1799a7043904a43b0c159
Author:     Tim Chen <tim.c.chen@linux.intel.com>
AuthorDate: Tue, 21 Jan 2014 15:36:22 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 9 Feb 2014 21:18:52 +0100

locking/mcs: Allow architecture specific asm files to be used for contended case

This patch allows each architecture to add its specific assembly optimized
arch_mcs_spin_lock_contended and arch_mcs_spinlock_uncontended for
MCS lock and unlock functions.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: AswinChandramouleeswaran <aswin@hp.com>
Cc: George Spelvin <linux@horizon.com>
Cc: Rik vanRiel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: MichelLespinasse <walken@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Figo.zhang" <figo1802@gmail.com>
Cc: "Paul E.McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew R Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1390347382.3138.67.camel@schen9-DESK
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/alpha/include/asm/Kbuild      |  1 +
 arch/arc/include/asm/Kbuild        |  1 +
 arch/arm/include/asm/Kbuild        |  1 +
 arch/arm64/include/asm/Kbuild      |  1 +
 arch/avr32/include/asm/Kbuild      |  1 +
 arch/blackfin/include/asm/Kbuild   |  1 +
 arch/c6x/include/asm/Kbuild        |  1 +
 arch/cris/include/asm/Kbuild       |  1 +
 arch/frv/include/asm/Kbuild        |  1 +
 arch/hexagon/include/asm/Kbuild    |  1 +
 arch/ia64/include/asm/Kbuild       |  1 +
 arch/m32r/include/asm/Kbuild       |  1 +
 arch/m68k/include/asm/Kbuild       |  1 +
 arch/metag/include/asm/Kbuild      |  1 +
 arch/microblaze/include/asm/Kbuild |  1 +
 arch/mips/include/asm/Kbuild       |  1 +
 arch/mn10300/include/asm/Kbuild    |  1 +
 arch/openrisc/include/asm/Kbuild   |  1 +
 arch/parisc/include/asm/Kbuild     |  1 +
 arch/powerpc/include/asm/Kbuild    |  1 +
 arch/s390/include/asm/Kbuild       |  1 +
 arch/score/include/asm/Kbuild      |  1 +
 arch/sh/include/asm/Kbuild         |  1 +
 arch/sparc/include/asm/Kbuild      |  1 +
 arch/tile/include/asm/Kbuild       |  1 +
 arch/um/include/asm/Kbuild         |  1 +
 arch/unicore32/include/asm/Kbuild  |  1 +
 arch/x86/include/asm/Kbuild        |  1 +
 arch/xtensa/include/asm/Kbuild     |  1 +
 include/asm-generic/mcs_spinlock.h | 13 +++++++++++++
 include/linux/mcs_spinlock.h       |  2 ++
 31 files changed, 44 insertions(+)

diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index 55a2b039..7736f42 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -3,5 +3,6 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild
index 54ceb91..e76fd79 100644
--- a/arch/arc/include/asm/Kbuild
+++ b/arch/arc/include/asm/Kbuild
@@ -22,6 +22,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += param.h
diff --git a/arch/arm/include/asm/Kbuild b/arch/arm/include/asm/Kbuild
index 3b20920..23e728e 100644
--- a/arch/arm/include/asm/Kbuild
+++ b/arch/arm/include/asm/Kbuild
@@ -14,6 +14,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += param.h
 generic-y += parport.h
diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index 54038be..3bdfdda 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -23,6 +23,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
diff --git a/arch/avr32/include/asm/Kbuild b/arch/avr32/include/asm/Kbuild
index 064ca3c..8b398ff 100644
--- a/arch/avr32/include/asm/Kbuild
+++ b/arch/avr32/include/asm/Kbuild
@@ -11,6 +11,7 @@ generic-y += hash.h
 generic-y += irq_regs.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += param.h
 generic-y += percpu.h
 generic-y += preempt.h
diff --git a/arch/blackfin/include/asm/Kbuild b/arch/blackfin/include/asm/Kbuild
index ca30a3d..0d93b9a 100644
--- a/arch/blackfin/include/asm/Kbuild
+++ b/arch/blackfin/include/asm/Kbuild
@@ -20,6 +20,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += mutex.h
diff --git a/arch/c6x/include/asm/Kbuild b/arch/c6x/include/asm/Kbuild
index dea0671..8dbdce8 100644
--- a/arch/c6x/include/asm/Kbuild
+++ b/arch/c6x/include/asm/Kbuild
@@ -25,6 +25,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += mmu.h
 generic-y += mmu_context.h
diff --git a/arch/cris/include/asm/Kbuild b/arch/cris/include/asm/Kbuild
index 7f8d1b1..056027f 100644
--- a/arch/cris/include/asm/Kbuild
+++ b/arch/cris/include/asm/Kbuild
@@ -9,6 +9,7 @@ generic-y += exec.h
 generic-y += hash.h
 generic-y += kvm_para.h
 generic-y += linkage.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/frv/include/asm/Kbuild b/arch/frv/include/asm/Kbuild
index 93428d0..babb933 100644
--- a/arch/frv/include/asm/Kbuild
+++ b/arch/frv/include/asm/Kbuild
@@ -2,5 +2,6 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/hexagon/include/asm/Kbuild b/arch/hexagon/include/asm/Kbuild
index 9f0eda4..eadcc11 100644
--- a/arch/hexagon/include/asm/Kbuild
+++ b/arch/hexagon/include/asm/Kbuild
@@ -27,6 +27,7 @@ generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += pci.h
diff --git a/arch/ia64/include/asm/Kbuild b/arch/ia64/include/asm/Kbuild
index 81ebef7..0da4aa2 100644
--- a/arch/ia64/include/asm/Kbuild
+++ b/arch/ia64/include/asm/Kbuild
@@ -3,6 +3,7 @@ generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += kvm_para.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += vtime.h
diff --git a/arch/m32r/include/asm/Kbuild b/arch/m32r/include/asm/Kbuild
index 8704221..5825a35 100644
--- a/arch/m32r/include/asm/Kbuild
+++ b/arch/m32r/include/asm/Kbuild
@@ -2,6 +2,7 @@
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/m68k/include/asm/Kbuild b/arch/m68k/include/asm/Kbuild
index f44ac8f..86b4c17 100644
--- a/arch/m68k/include/asm/Kbuild
+++ b/arch/m68k/include/asm/Kbuild
@@ -16,6 +16,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += mutex.h
 generic-y += percpu.h
diff --git a/arch/metag/include/asm/Kbuild b/arch/metag/include/asm/Kbuild
index ac22144..c29ead8 100644
--- a/arch/metag/include/asm/Kbuild
+++ b/arch/metag/include/asm/Kbuild
@@ -24,6 +24,7 @@ generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += param.h
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index 4b5f122..1f590ab 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -3,6 +3,7 @@ generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += syscalls.h
 generic-y += trace_clock.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 82ee17a..0543918 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -4,6 +4,7 @@ generic-y += current.h
 generic-y += emergency-restart.h
 generic-y += hash.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += parport.h
 generic-y += percpu.h
diff --git a/arch/mn10300/include/asm/Kbuild b/arch/mn10300/include/asm/Kbuild
index da3b2f5..cbc6b9b 100644
--- a/arch/mn10300/include/asm/Kbuild
+++ b/arch/mn10300/include/asm/Kbuild
@@ -3,5 +3,6 @@ generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += exec.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/openrisc/include/asm/Kbuild b/arch/openrisc/include/asm/Kbuild
index f62a67a..480af0d 100644
--- a/arch/openrisc/include/asm/Kbuild
+++ b/arch/openrisc/include/asm/Kbuild
@@ -35,6 +35,7 @@ generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += kvm_para.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += module.h
 generic-y += msgbuf.h
diff --git a/arch/parisc/include/asm/Kbuild b/arch/parisc/include/asm/Kbuild
index 958b79a..ecf25e6 100644
--- a/arch/parisc/include/asm/Kbuild
+++ b/arch/parisc/include/asm/Kbuild
@@ -14,6 +14,7 @@ generic-y += kdebug.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += param.h
 generic-y += percpu.h
diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index b618c41..3fb1bc4 100644
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -1,6 +1,7 @@
 
 generic-y += clkdev.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += rwsem.h
 generic-y += trace_clock.h
diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 482f492..57892a8 100644
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -2,5 +2,6 @@
 
 generic-y += clkdev.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
diff --git a/arch/score/include/asm/Kbuild b/arch/score/include/asm/Kbuild
index e92319f..4630cf2 100644
--- a/arch/score/include/asm/Kbuild
+++ b/arch/score/include/asm/Kbuild
@@ -5,6 +5,7 @@ header-y +=
 generic-y += barrier.h
 generic-y += clkdev.h
 generic-y += hash.h
+generic-y += mcs_spinlock.h
 generic-y += preempt.h
 generic-y += trace_clock.h
 generic-y += xor.h
diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
index 85c214e..c19e47d 100644
--- a/arch/sh/include/asm/Kbuild
+++ b/arch/sh/include/asm/Kbuild
@@ -15,6 +15,7 @@ generic-y += irq_regs.h
 generic-y += kvm_para.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += msgbuf.h
 generic-y += param.h
diff --git a/arch/sparc/include/asm/Kbuild b/arch/sparc/include/asm/Kbuild
index 8215028..a458218 100644
--- a/arch/sparc/include/asm/Kbuild
+++ b/arch/sparc/include/asm/Kbuild
@@ -11,6 +11,7 @@ generic-y += irq_regs.h
 generic-y += linkage.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += module.h
 generic-y += mutex.h
 generic-y += preempt.h
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index e0b1ed9..0aa5675 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/arch/tile/include/asm/Kbuild
@@ -19,6 +19,7 @@ generic-y += ipcbuf.h
 generic-y += irq_regs.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += msgbuf.h
 generic-y += mutex.h
 generic-y += param.h
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 215e05d..a5e4b60 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -15,6 +15,7 @@ generic-y += hw_irq.h
 generic-y += io.h
 generic-y += irq_regs.h
 generic-y += kdebug.h
+generic-y += mcs_spinlock.h
 generic-y += mutex.h
 generic-y += param.h
 generic-y += pci.h
diff --git a/arch/unicore32/include/asm/Kbuild b/arch/unicore32/include/asm/Kbuild
index ad2c737..1e5fb87 100644
--- a/arch/unicore32/include/asm/Kbuild
+++ b/arch/unicore32/include/asm/Kbuild
@@ -25,6 +25,7 @@ generic-y += irq_regs.h
 generic-y += kdebug.h
 generic-y += kmap_types.h
 generic-y += local.h
+generic-y += mcs_spinlock.h
 generic-y += mman.h
 generic-y += module.h
 generic-y += msgbuf.h
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 7f66985..a8fee07 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -5,3 +5,4 @@ genhdr-y += unistd_64.h
 genhdr-y += unistd_x32.h
 
 generic-y += clkdev.h
+generic-y += mcs_spinlock.h
diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild
index 223280d..c3d20ba 100644
--- a/arch/xtensa/include/asm/Kbuild
+++ b/arch/xtensa/include/asm/Kbuild
@@ -18,6 +18,7 @@ generic-y += kvm_para.h
 generic-y += linkage.h
 generic-y += local.h
 generic-y += local64.h
+generic-y += mcs_spinlock.h
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += resource.h
diff --git a/include/asm-generic/mcs_spinlock.h b/include/asm-generic/mcs_spinlock.h
new file mode 100644
index 0000000..10cd4ff
--- /dev/null
+++ b/include/asm-generic/mcs_spinlock.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_MCS_SPINLOCK_H
+#define __ASM_MCS_SPINLOCK_H
+
+/*
+ * Architectures can define their own:
+ *
+ *   arch_mcs_spin_lock_contended(l)
+ *   arch_mcs_spin_unlock_contended(l)
+ *
+ * See kernel/locking/mcs_spinlock.c.
+ */
+
+#endif /* __ASM_MCS_SPINLOCK_H */
diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index e9a4d74..f2a5c63 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -12,6 +12,8 @@
 #ifndef __LINUX_MCS_SPINLOCK_H
 #define __LINUX_MCS_SPINLOCK_H
 
+#include <asm/mcs_spinlock.h>
+
 struct mcs_spinlock {
 	struct mcs_spinlock *next;
 	int locked; /* 1 if lock acquired */