forked from luck/tmp_suning_uos_patched
locking/atomics, workqueue: Convert ACCESS_ONCE() to READ_ONCE()/WRITE_ONCE()
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't currently harmful. However, for some features it is necessary to instrument reads and writes separately, which is not possible with ACCESS_ONCE(). This distinction is critical to correct operation. It's possible to transform the bulk of kernel code using the Coccinelle script below. However, this doesn't handle comments, leaving references to ACCESS_ONCE() instances which have been removed. As a preparatory step, this patch converts the workqueue code and comments to use {READ,WRITE}_ONCE() consistently. ---- virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-12-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
564cbc8793
commit
c95491ed6d
|
@ -4647,7 +4647,7 @@ static void rebind_workers(struct worker_pool *pool)
|
|||
* concurrency management. Note that when or whether
|
||||
* @worker clears REBOUND doesn't affect correctness.
|
||||
*
|
||||
* ACCESS_ONCE() is necessary because @worker->flags may be
|
||||
* WRITE_ONCE() is necessary because @worker->flags may be
|
||||
* tested without holding any lock in
|
||||
* wq_worker_waking_up(). Without it, NOT_RUNNING test may
|
||||
* fail incorrectly leading to premature concurrency
|
||||
|
@ -4656,7 +4656,7 @@ static void rebind_workers(struct worker_pool *pool)
|
|||
WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
|
||||
worker_flags |= WORKER_REBOUND;
|
||||
worker_flags &= ~WORKER_UNBOUND;
|
||||
ACCESS_ONCE(worker->flags) = worker_flags;
|
||||
WRITE_ONCE(worker->flags, worker_flags);
|
||||
}
|
||||
|
||||
spin_unlock_irq(&pool->lock);
|
||||
|
|
Loading…
Reference in New Issue
Block a user