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locking/spinlock: Update spin_unlock_wait() users

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With the modified semantics of spin_unlock_wait() a number of
explicit barriers can be removed. Also update the comment for the
do_exit() usecase, as that was somewhat stale/obscure.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-05-24 14:45:21 +02:00 committed by Ingo Molnar
parent 726328d92a
commit be3e784498
3 changed files with 6 additions and 4 deletions
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1
ipc/sem.c
View File

@ -282,7 +282,6 @@ static void sem_wait_array(struct sem_array *sma)
sem = sma->sem_base + i;
spin_unlock_wait(&sem->lock);
}
smp_acquire__after_ctrl_dep();
}
/*

8
kernel/exit.c
View File

@ -700,10 +700,14 @@ void do_exit(long code)
exit_signals(tsk); /* sets PF_EXITING */
/*
* tsk->flags are checked in the futex code to protect against
* an exiting task cleaning up the robust pi futexes.
* Ensure that all new tsk->pi_lock acquisitions must observe
* PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
*/
smp_mb();
/*
* Ensure that we must observe the pi_state in exit_mm() ->
* mm_release() -> exit_pi_state_list().
*/
raw_spin_unlock_wait(&tsk->pi_lock);
if (unlikely(in_atomic())) {

1
kernel/task_work.c
View File

@ -108,7 +108,6 @@ void task_work_run(void)
* fail, but it can play with *work and other entries.
*/
raw_spin_unlock_wait(&task->pi_lock);
smp_mb();
do {
next = work->next;