block: Make blk_cleanup_queue() wait until request_fn finished
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>
diff --git a/block/blk-core.c b/block/blk-core.c
index 9fb2353..473015e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -309,7 +309,16 @@
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 @@
__blk_run_queue(q);
drain |= q->nr_rqs_elvpriv;
+ drain |= q->request_fn_active;
/*
* Unfortunately, requests are queued at and tracked from