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rcu-tasks: Remove preemption disablement around srcu_read_[un]lock() calls 

[ Upstream commit 4475709295 ]

Ever since the following commit:

	5a41344a3d ("srcu: Simplify __srcu_read_unlock() via this_cpu_dec()")

SRCU doesn't rely anymore on preemption to be disabled in order to
modify the per-CPU counter. And even then it used to be done from the API
itself.

Therefore and after checking further, it appears to be safe to remove
the preemption disablement around __srcu_read_[un]lock() in
exit_tasks_rcu_start() and exit_tasks_rcu_finish()

Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Stable-dep-of: 28319d6dc5 ("rcu-tasks: Fix synchronize_rcu_tasks() VS zap_pid_ns_processes()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Frederic Weisbecker 2022-11-25 14:54:59 +01:00 committed by Greg Kroah-Hartman
parent a2b0cda452
commit 24f259ce3a
1 changed files with 0 additions and 4 deletions
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4
kernel/rcu/tasks.h
View File

@ -1008,9 +1008,7 @@ EXPORT_SYMBOL_GPL(show_rcu_tasks_classic_gp_kthread);
*/ */
void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu) void exit_tasks_rcu_start(void) __acquires(&tasks_rcu_exit_srcu)
{ {
preempt_disable();
current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu); current->rcu_tasks_idx = __srcu_read_lock(&tasks_rcu_exit_srcu);
preempt_enable();
} }
/* /*
@ -1022,9 +1020,7 @@ void exit_tasks_rcu_finish(void) __releases(&tasks_rcu_exit_srcu)
{ {
struct task_struct *t = current; struct task_struct *t = current;
preempt_disable();
__srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx); __srcu_read_unlock(&tasks_rcu_exit_srcu, t->rcu_tasks_idx);
preempt_enable();
exit_tasks_rcu_finish_trace(t); exit_tasks_rcu_finish_trace(t);
} }