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Commit 18c9a6bb authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

percpu-refcount: Introduce percpu_ref_resurrect() 



This function will be used in a later patch to switch the struct
request_queue q_usage_counter from killed back to live. In contrast
to percpu_ref_reinit(), this new function does not require that the
refcount is zero.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0d25bd07

include/linux/percpu-refcount.h

+1 −0
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ void percpu_ref_switch_to_atomic_sync(struct percpu_ref *ref); 
void percpu_ref_switch_to_percpu(struct percpu_ref *ref);

void percpu_ref_kill_and_confirm(struct percpu_ref *ref,

				 percpu_ref_func_t *confirm_kill);

void percpu_ref_resurrect(struct percpu_ref *ref);

void percpu_ref_reinit(struct percpu_ref *ref);



/**

lib/percpu-refcount.c

+26 −2
Original line number Diff line number Diff line
@@ -356,11 +356,35 @@ EXPORT_SYMBOL_GPL(percpu_ref_kill_and_confirm); 
 */

void percpu_ref_reinit(struct percpu_ref *ref)

{

	WARN_ON_ONCE(!percpu_ref_is_zero(ref));



	percpu_ref_resurrect(ref);

}

EXPORT_SYMBOL_GPL(percpu_ref_reinit);



/**

 * percpu_ref_resurrect - modify a percpu refcount from dead to live

 * @ref: perpcu_ref to resurrect

 *

 * Modify @ref so that it's in the same state as before percpu_ref_kill() was

 * called. @ref must be dead but must not yet have exited.

 *

 * If @ref->release() frees @ref then the caller is responsible for

 * guaranteeing that @ref->release() does not get called while this

 * function is in progress.

 *

 * Note that percpu_ref_tryget[_live]() are safe to perform on @ref while

 * this function is in progress.

 */

void percpu_ref_resurrect(struct percpu_ref *ref)

{

	unsigned long __percpu *percpu_count;

	unsigned long flags;



	spin_lock_irqsave(&percpu_ref_switch_lock, flags);



	WARN_ON_ONCE(!percpu_ref_is_zero(ref));

	WARN_ON_ONCE(!(ref->percpu_count_ptr & __PERCPU_REF_DEAD));

	WARN_ON_ONCE(__ref_is_percpu(ref, &percpu_count));



	ref->percpu_count_ptr &= ~__PERCPU_REF_DEAD;

	percpu_ref_get(ref);
@@ -368,4 +392,4 @@ void percpu_ref_reinit(struct percpu_ref *ref) 


	spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);

}

EXPORT_SYMBOL_GPL(percpu_ref_reinit);
 
EXPORT_SYMBOL_GPL(percpu_ref_resurrect);