On Thu, 2017-02-16 at 16:12 +0100, Hannes Reinecke wrote:
> +struct scsi_device *scsi_device_from_queue(struct request_queue *q)
> +{
> + struct scsi_device *sdev = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(q->queue_lock, flags);
> + if (q->mq_ops) {
> + if (q->mq_ops == &scsi_mq_ops)
> + sdev = q->queuedata;
> + } else if (q->request_fn == scsi_request_fn)
> + sdev = q->queuedata;
> + if (!sdev || !get_device(&sdev->sdev_gendev))
> + sdev = NULL;
> + spin_unlock_irqrestore(q->queue_lock, flags);
> +
> + return sdev;
> +}
Hello Hannes,
Do we need to take the queue lock? Neither q->mq_ops nor q->request_fn are
modified after a block device has been created. q->queuedata is not modified
by any SCSI driver after it has been set. And since the caller of
scsi_device_from_queue() has to guarantee that the queue does not disappear
while this function is in progress, the queue lock does not have to be held
around the get_device() call either. Otherwise this patch looks fine to me.
Bart.
