[RFC PATCH 1/1] smp: Change function signatures to use call_single_data_t

[Leonardo Bras <leobras@redhat.com>]

call_single_data_t is a size-aligned typedef of struct __call_single_data.

This alignment is desirable in order to have smp_call_function*() avoid
bouncing an extra cacheline in case of an unaligned csd, given this
would hurt performance.

Since the removal of struct request->csd in commit 660e802c76c8
("blk-mq: use percpu csd to remote complete instead of per-rq csd") there
are no current users of smp_call_function*() with unaligned csd.

Change every 'struct __call_single_data' function parameter to
'call_single_data_t', so we have warnings if any new code tries to
introduce an smp_call_function*() call with unaligned csd.

Signed-off-by: Leonardo Bras <leobras@redhat.com>
---
 include/linux/smp.h        |  2 +-
 include/trace/events/csd.h |  8 ++++----
 kernel/smp.c               | 26 +++++++++++++-------------
 kernel/up.c                |  2 +-
 4 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/include/linux/smp.h b/include/linux/smp.h
index 91ea4a67f8ca..e87520dc2959 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -53,7 +53,7 @@ int smp_call_function_single(int cpuid, smp_call_func_t func, void *info,
 void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func,
 			   void *info, bool wait, const struct cpumask *mask);
 
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd);
+int smp_call_function_single_async(int cpu, call_single_data_t *csd);
 
 /*
  * Cpus stopping functions in panic. All have default weak definitions.
diff --git a/include/trace/events/csd.h b/include/trace/events/csd.h
index 67e9d01f80c2..58cc83b99c34 100644
--- a/include/trace/events/csd.h
+++ b/include/trace/events/csd.h
@@ -12,7 +12,7 @@ TRACE_EVENT(csd_queue_cpu,
 	TP_PROTO(const unsigned int cpu,
 		unsigned long callsite,
 		smp_call_func_t func,
-		struct __call_single_data *csd),
+		call_single_data_t *csd),
 
 	TP_ARGS(cpu, callsite, func, csd),
 
@@ -39,7 +39,7 @@ TRACE_EVENT(csd_queue_cpu,
  */
 DECLARE_EVENT_CLASS(csd_function,
 
-	TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
+	TP_PROTO(smp_call_func_t func, call_single_data_t *csd),
 
 	TP_ARGS(func, csd),
 
@@ -57,12 +57,12 @@ DECLARE_EVENT_CLASS(csd_function,
 );
 
 DEFINE_EVENT(csd_function, csd_function_entry,
-	TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
+	TP_PROTO(smp_call_func_t func, call_single_data_t *csd),
 	TP_ARGS(func, csd)
 );
 
 DEFINE_EVENT(csd_function, csd_function_exit,
-	TP_PROTO(smp_call_func_t func, struct __call_single_data *csd),
+	TP_PROTO(smp_call_func_t func, call_single_data_t *csd),
 	TP_ARGS(func, csd)
 );
 
diff --git a/kernel/smp.c b/kernel/smp.c
index 8455a53465af..8c714583786b 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -127,7 +127,7 @@ send_call_function_ipi_mask(struct cpumask *mask)
 }
 
 static __always_inline void
-csd_do_func(smp_call_func_t func, void *info, struct __call_single_data *csd)
+csd_do_func(smp_call_func_t func, void *info, call_single_data_t *csd)
 {
 	trace_csd_function_entry(func, csd);
 	func(info);
@@ -174,7 +174,7 @@ module_param(csd_lock_timeout, ulong, 0444);
 static atomic_t csd_bug_count = ATOMIC_INIT(0);
 
 /* Record current CSD work for current CPU, NULL to erase. */
-static void __csd_lock_record(struct __call_single_data *csd)
+static void __csd_lock_record(call_single_data_t *csd)
 {
 	if (!csd) {
 		smp_mb(); /* NULL cur_csd after unlock. */
@@ -189,13 +189,13 @@ static void __csd_lock_record(struct __call_single_data *csd)
 		  /* Or before unlock, as the case may be. */
 }
 
-static __always_inline void csd_lock_record(struct __call_single_data *csd)
+static __always_inline void csd_lock_record(call_single_data_t *csd)
 {
 	if (static_branch_unlikely(&csdlock_debug_enabled))
 		__csd_lock_record(csd);
 }
 
-static int csd_lock_wait_getcpu(struct __call_single_data *csd)
+static int csd_lock_wait_getcpu(call_single_data_t *csd)
 {
 	unsigned int csd_type;
 
@@ -210,7 +210,7 @@ static int csd_lock_wait_getcpu(struct __call_single_data *csd)
  * the CSD_TYPE_SYNC/ASYNC types provide the destination CPU,
  * so waiting on other types gets much less information.
  */
-static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *ts1, int *bug_id)
+static bool csd_lock_wait_toolong(call_single_data_t *csd, u64 ts0, u64 *ts1, int *bug_id)
 {
 	int cpu = -1;
 	int cpux;
@@ -276,7 +276,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 *
  * previous function call. For multi-cpu calls its even more interesting
  * as we'll have to ensure no other cpu is observing our csd.
  */
-static void __csd_lock_wait(struct __call_single_data *csd)
+static void __csd_lock_wait(call_single_data_t *csd)
 {
 	int bug_id = 0;
 	u64 ts0, ts1;
@@ -290,7 +290,7 @@ static void __csd_lock_wait(struct __call_single_data *csd)
 	smp_acquire__after_ctrl_dep();
 }
 
-static __always_inline void csd_lock_wait(struct __call_single_data *csd)
+static __always_inline void csd_lock_wait(call_single_data_t *csd)
 {
 	if (static_branch_unlikely(&csdlock_debug_enabled)) {
 		__csd_lock_wait(csd);
@@ -300,17 +300,17 @@ static __always_inline void csd_lock_wait(struct __call_single_data *csd)
 	smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
 }
 #else
-static void csd_lock_record(struct __call_single_data *csd)
+static void csd_lock_record(call_single_data_t *csd)
 {
 }
 
-static __always_inline void csd_lock_wait(struct __call_single_data *csd)
+static __always_inline void csd_lock_wait(call_single_data_t *csd)
 {
 	smp_cond_load_acquire(&csd->node.u_flags, !(VAL & CSD_FLAG_LOCK));
 }
 #endif
 
-static __always_inline void csd_lock(struct __call_single_data *csd)
+static __always_inline void csd_lock(call_single_data_t *csd)
 {
 	csd_lock_wait(csd);
 	csd->node.u_flags |= CSD_FLAG_LOCK;
@@ -323,7 +323,7 @@ static __always_inline void csd_lock(struct __call_single_data *csd)
 	smp_wmb();
 }
 
-static __always_inline void csd_unlock(struct __call_single_data *csd)
+static __always_inline void csd_unlock(call_single_data_t *csd)
 {
 	WARN_ON(!(csd->node.u_flags & CSD_FLAG_LOCK));
 
@@ -376,7 +376,7 @@ void __smp_call_single_queue(int cpu, struct llist_node *node)
  * for execution on the given CPU. data must already have
  * ->func, ->info, and ->flags set.
  */
-static int generic_exec_single(int cpu, struct __call_single_data *csd)
+static int generic_exec_single(int cpu, call_single_data_t *csd)
 {
 	if (cpu == smp_processor_id()) {
 		smp_call_func_t func = csd->func;
@@ -667,7 +667,7 @@ EXPORT_SYMBOL(smp_call_function_single);
  *
  * Return: %0 on success or negative errno value on error
  */
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
+int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 {
 	int err = 0;
 
diff --git a/kernel/up.c b/kernel/up.c
index a38b8b095251..df50828cc2f0 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -25,7 +25,7 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 }
 EXPORT_SYMBOL(smp_call_function_single);
 
-int smp_call_function_single_async(int cpu, struct __call_single_data *csd)
+int smp_call_function_single_async(int cpu, call_single_data_t *csd)
 {
 	unsigned long flags;
 
-- 
2.42.0