null_blk: guarantee device restart in all irq modes
In single-queue (block layer) mode,the function null_rq_prep_fn stops
the device if alloc_cmd fails. Then, once stopped, the device must be
restarted on the next command completion, so that the request(s) for
which alloc_cmd failed can be requeued. Otherwise the device hangs.
Unfortunately, device restart is currently performed only for delayed
completions, i.e., in irqmode==2. This fact causes hangs, for the
above reasons, with the other irqmodes in combination with single-queue
block layer.
This commits addresses this issue by making sure that, if stopped, the
device is properly restarted for all irqmodes on completions.
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna AVanzini <avanzini@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 08932f5..cf65619 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -217,6 +217,8 @@
static void end_cmd(struct nullb_cmd *cmd)
{
+ struct request_queue *q = NULL;
+
switch (queue_mode) {
case NULL_Q_MQ:
blk_mq_end_request(cmd->rq, 0);
@@ -227,27 +229,28 @@
break;
case NULL_Q_BIO:
bio_endio(cmd->bio);
- break;
+ goto free_cmd;
}
+ if (cmd->rq)
+ q = cmd->rq->q;
+
+ /* Restart queue if needed, as we are freeing a tag */
+ if (q && !q->mq_ops && blk_queue_stopped(q)) {
+ unsigned long flags;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ if (blk_queue_stopped(q))
+ blk_start_queue(q);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+ }
+free_cmd:
free_cmd(cmd);
}
static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
{
- struct nullb_cmd *cmd = container_of(timer, struct nullb_cmd, timer);
- struct request_queue *q = NULL;
-
- if (cmd->rq)
- q = cmd->rq->q;
-
- if (q && !q->mq_ops && blk_queue_stopped(q)) {
- spin_lock(q->queue_lock);
- if (blk_queue_stopped(q))
- blk_start_queue(q);
- spin_unlock(q->queue_lock);
- }
- end_cmd(cmd);
+ end_cmd(container_of(timer, struct nullb_cmd, timer));
return HRTIMER_NORESTART;
}