From: Boqun Feng <boqun.feng@gmail.com>
To: rcu@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Josh Triplett <josh@joshtriplett.org>,
Boqun Feng <boqun.feng@gmail.com>,
Uladzislau Rezki <urezki@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Zqiang <qiang.zhang1211@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Shuah Khan <shuah@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev,
Ankur Arora <ankur.a.arora@oracle.com>
Subject: [PATCH rcu 02/11] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY
Date: Mon, 24 Feb 2025 19:55:07 -0800 [thread overview]
Message-ID: <20250225035516.26443-3-boqun.feng@gmail.com> (raw)
In-Reply-To: <20250225035516.26443-1-boqun.feng@gmail.com>
From: Ankur Arora <ankur.a.arora@oracle.com>
Replace mentions of PREEMPT_AUTO with PREEMPT_LAZY.
Also, since PREMPT_LAZY implies PREEMPTION, we can reduce the
TASKS_RCU selection criteria from this:
NEED_TASKS_RCU && (PREEMPTION || PREEMPT_AUTO)
to this:
NEED_TASKS_RCU && PREEMPTION
CC: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
---
include/linux/srcutiny.h | 2 +-
kernel/rcu/Kconfig | 2 +-
kernel/rcu/srcutiny.c | 14 +++++++-------
3 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 1321da803274..31b59b4be2a7 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -64,7 +64,7 @@ static inline int __srcu_read_lock(struct srcu_struct *ssp)
{
int idx;
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1;
WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1);
preempt_enable();
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index b9b6bc55185d..e2206f3a070c 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -91,7 +91,7 @@ config NEED_TASKS_RCU
config TASKS_RCU
bool
- default NEED_TASKS_RCU && (PREEMPTION || PREEMPT_AUTO)
+ default NEED_TASKS_RCU && PREEMPTION
select IRQ_WORK
config FORCE_TASKS_RUDE_RCU
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 4dcbf8aa80ff..f688bdad293e 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -98,7 +98,7 @@ void __srcu_read_unlock(struct srcu_struct *ssp, int idx)
{
int newval;
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
newval = READ_ONCE(ssp->srcu_lock_nesting[idx]) - 1;
WRITE_ONCE(ssp->srcu_lock_nesting[idx], newval);
preempt_enable();
@@ -120,7 +120,7 @@ void srcu_drive_gp(struct work_struct *wp)
struct srcu_struct *ssp;
ssp = container_of(wp, struct srcu_struct, srcu_work);
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
if (ssp->srcu_gp_running || ULONG_CMP_GE(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max))) {
preempt_enable();
return; /* Already running or nothing to do. */
@@ -138,7 +138,7 @@ void srcu_drive_gp(struct work_struct *wp)
WRITE_ONCE(ssp->srcu_gp_waiting, true); /* srcu_read_unlock() wakes! */
preempt_enable();
swait_event_exclusive(ssp->srcu_wq, !READ_ONCE(ssp->srcu_lock_nesting[idx]));
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
WRITE_ONCE(ssp->srcu_gp_waiting, false); /* srcu_read_unlock() cheap. */
WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1);
preempt_enable();
@@ -159,7 +159,7 @@ void srcu_drive_gp(struct work_struct *wp)
* at interrupt level, but the ->srcu_gp_running checks will
* straighten that out.
*/
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
WRITE_ONCE(ssp->srcu_gp_running, false);
idx = ULONG_CMP_LT(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max));
preempt_enable();
@@ -172,7 +172,7 @@ static void srcu_gp_start_if_needed(struct srcu_struct *ssp)
{
unsigned long cookie;
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
cookie = get_state_synchronize_srcu(ssp);
if (ULONG_CMP_GE(READ_ONCE(ssp->srcu_idx_max), cookie)) {
preempt_enable();
@@ -199,7 +199,7 @@ void call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
rhp->func = func;
rhp->next = NULL;
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
local_irq_save(flags);
*ssp->srcu_cb_tail = rhp;
ssp->srcu_cb_tail = &rhp->next;
@@ -261,7 +261,7 @@ unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp)
{
unsigned long ret;
- preempt_disable(); // Needed for PREEMPT_AUTO
+ preempt_disable(); // Needed for PREEMPT_LAZY
ret = get_state_synchronize_srcu(ssp);
srcu_gp_start_if_needed(ssp);
preempt_enable();
--
2.39.5 (Apple Git-154)
next prev parent reply other threads:[~2025-02-25 3:55 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-25 3:55 [PATCH rcu 00/11] Lazy Preempt changes for v6.15 Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 01/11] rcu: fix header guard for rcu_all_qs() Boqun Feng
2025-02-25 3:55 ` Boqun Feng [this message]
2025-02-25 3:55 ` [PATCH rcu 03/11] sched: update __cond_resched comment about RCU quiescent states Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 04/11] rcu: handle unstable rdp in rcu_read_unlock_strict() Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 05/11] rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 06/11] osnoise: provide quiescent states Boqun Feng
2025-03-04 19:21 ` Steven Rostedt
2025-03-05 2:54 ` Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 07/11] rcutorture: Update rcutorture_one_extend_check() for lazy preemption Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 08/11] rcutorture: Update ->extendables check " Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 09/11] rcu: limit PREEMPT_RCU configurations Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 10/11] rcutorture: Make scenario TREE10 build CONFIG_PREEMPT_LAZY=y Boqun Feng
2025-02-25 3:55 ` [PATCH rcu 11/11] rcutorture: Make scenario TREE07 " Boqun Feng
2025-02-27 23:33 ` [PATCH rcu 00/11] Lazy Preempt changes for v6.15 Ankur Arora
2025-02-27 23:47 ` Paul E. McKenney
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