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| author | Peter Zijlstra <peterz@infradead.org> | 2016-05-24 14:45:21 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-06-14 11:55:15 +0200 |
| commit | be3e7844980352756de4261b276ee2ba5be7a26b (patch) | |
| tree | 977f32f488649a6c77dcec9190d36fddc3df6b69 | |
| parent | 726328d92a42b6d4b76078e2659f43067f82c4e8 (diff) | |
| download | linux-be3e7844980352756de4261b276ee2ba5be7a26b.tar.bz2 | |
locking/spinlock: Update spin_unlock_wait() users
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>
| -rw-r--r-- | ipc/sem.c | 1 | ||||
| -rw-r--r-- | kernel/exit.c | 8 | ||||
| -rw-r--r-- | kernel/task_work.c | 1 |
3 files changed, 6 insertions, 4 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 84dff3df11a4..ae72b3cddc8d 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -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(); } /* diff --git a/kernel/exit.c b/kernel/exit.c index 9e6e1356e6bb..0b40791b9e70 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -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())) { diff --git a/kernel/task_work.c b/kernel/task_work.c index 53fa971d000d..6ab4842b00e8 100644 --- a/kernel/task_work.c +++ b/kernel/task_work.c @@ -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; |