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block: Make blk_cleanup_queue() wait until request_fn finished

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Some request_fn implementations, e.g. scsi_request_fn(), unlock
the queue lock internally. This may result in multiple threads
executing request_fn for the same queue simultaneously. Keep
track of the number of active request_fn calls and make sure that
blk_cleanup_queue() waits until all active request_fn invocations
have finished. A block driver may start cleaning up resources
needed by its request_fn as soon as blk_cleanup_queue() finished,
so blk_cleanup_queue() must wait for all outstanding request_fn
invocations to finish.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reported-by: Chanho Min <chanho.min@lge.com>
Cc: James Bottomley <JBottomley@Parallels.com>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche 2012-11-28 13:46:45 +01:00 committed by Jens Axboe
parent 704605711e
commit 24faf6f604
2 changed files with 16 additions and 0 deletions
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10
block/blk-core.c
View File

@ -309,7 +309,16 @@ inline void __blk_run_queue_uncond(struct request_queue *q)
if (unlikely(blk_queue_dead(q)))
return;
/*
* Some request_fn implementations, e.g. scsi_request_fn(), unlock
* the queue lock internally. As a result multiple threads may be
* running such a request function concurrently. Keep track of the
* number of active request_fn invocations such that blk_drain_queue()
* can wait until all these request_fn calls have finished.
*/
q->request_fn_active++;
q->request_fn(q);
q->request_fn_active--;
}
/**
@ -408,6 +417,7 @@ static void __blk_drain_queue(struct request_queue *q, bool drain_all)
__blk_run_queue(q);
drain |= q->nr_rqs_elvpriv;
drain |= q->request_fn_active;
/*
* Unfortunately, requests are queued at and tracked from

6
include/linux/blkdev.h
View File

@ -378,6 +378,12 @@ struct request_queue {
unsigned int nr_sorted;
unsigned int in_flight[2];
/*
* Number of active block driver functions for which blk_drain_queue()
* must wait. Must be incremented around functions that unlock the
* queue_lock internally, e.g. scsi_request_fn().
*/
unsigned int request_fn_active;
unsigned int rq_timeout;
struct timer_list timeout;