From 23a9b748a3d27f67cdb078fcb891a920285e75d9 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 29 Jun 2017 12:08:26 -0700 Subject: sched: Replace spin_unlock_wait() with lock/unlock pair There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore replaces the spin_unlock_wait() call in do_task_dead() with spin_lock() followed immediately by spin_unlock(). This should be safe from a performance perspective because the lock is this tasks ->pi_lock, and this is called only after the task exits. Signed-off-by: Paul E. McKenney Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon Cc: Alan Stern Cc: Andrea Parri Cc: Linus Torvalds [ paulmck: Drop smp_mb() based on Peter Zijlstra's analysis: http://lkml.kernel.org/r/20170811144150.26gowhxte7ri5fpk@hirez.programming.kicks-ass.net ] --- kernel/sched/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/sched') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 17c667b427b4..5d22323ae099 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3352,8 +3352,8 @@ void __noreturn do_task_dead(void) * To avoid it, we have to wait for releasing tsk->pi_lock which * is held by try_to_wake_up() */ - smp_mb(); - raw_spin_unlock_wait(¤t->pi_lock); + raw_spin_lock_irq(¤t->pi_lock); + raw_spin_unlock_irq(¤t->pi_lock); /* Causes final put_task_struct in finish_task_switch(): */ __set_current_state(TASK_DEAD); -- cgit v1.2.3