Some request_fn implementations, e.g. scsi_request_fn(), unlock
the queue lock. 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.
Reported-by: Chanho Min <chanho.min@xxxxxxx>
Cc: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Cc: Mike Christie <michaelc@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/blk-core.c | 3 +++
include/linux/blkdev.h | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/block/blk-core.c b/block/blk-core.c
index 2f1be7a..7662d83 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -308,7 +308,9 @@ void inline __blk_run_queue_uncond(struct request_queue *q)
if (unlikely(blk_queue_dead(q)))
return;
+ q->request_fn_active++;
q->request_fn(q);
+ q->request_fn_active--;
}
/**
@@ -407,6 +409,7 @@ 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
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8bc46c2..c9d233e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -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;
--
1.7.10.4
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