null_blk: guarantee device restart in all irq modes (cf8ecc5a) · Commits · 戴 / test

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>

drivers/block/null_blk.c

+15 −12

Original line number	Diff line number	Diff line
		@@ -217,6 +217,8 @@ static struct nullb_cmd alloc_cmd(struct nullb_queue nq, int can_wait)

		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 @@ static void end_cmd(struct nullb_cmd *cmd)
		break;
		case NULL_Q_BIO:
		bio_endio(cmd->bio);
		break;
		goto 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;

		/* Restart queue if needed, as we are freeing a tag */
		if (q && !q->mq_ops && blk_queue_stopped(q)) {
		spin_lock(q->queue_lock);
		unsigned long flags;

		spin_lock_irqsave(q->queue_lock, flags);
		if (blk_queue_stopped(q))
		blk_start_queue(q);
		spin_unlock(q->queue_lock);
		spin_unlock_irqrestore(q->queue_lock, flags);
		}
		end_cmd(cmd);
		free_cmd:
		free_cmd(cmd);
		}

		static enum hrtimer_restart null_cmd_timer_expired(struct hrtimer *timer)
		{
		end_cmd(container_of(timer, struct nullb_cmd, timer));

		return HRTIMER_NORESTART;
		}

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