Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit cf8ecc5a authored by Arianna Avanzini's avatar Arianna Avanzini Committed by Jens Axboe
Browse files

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: default avatarPaolo Valente <paolo.valente@unimore.it>
Signed-off-by: default avatarArianna AVanzini <avanzini@google.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 3c395a96

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;

}