Messages in this thread | | | Subject | Re: [PATCH V3] scsi: core: use blk_mq_requeue_request in __scsi_queue_insert | From | "jianchao.wang" <> | Date | Sat, 3 Mar 2018 09:41:40 +0800 |
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Hi Bart
Thanks for your kindly response and directive.
On 03/03/2018 12:31 AM, Bart Van Assche wrote: > On Fri, 2018-03-02 at 11:31 +0800, Jianchao Wang wrote: >> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >> index a86df9c..d2f1838 100644 >> --- a/drivers/scsi/scsi_lib.c >> +++ b/drivers/scsi/scsi_lib.c >> @@ -191,7 +191,13 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy) >> */ >> cmd->result = 0; >> if (q->mq_ops) { >> - scsi_mq_requeue_cmd(cmd); >> + /* >> + * scsi_device.sdev_gendev will be get every time in .get_budget and >> + * be put in scsi_end_request. Hence we need to put the reference >> + * here when we decide to requeue request. >> + */ >> + blk_mq_requeue_request(cmd->request, true); >> + put_device(&device->sdev_gendev); >> return; >> } >> spin_lock_irqsave(q->queue_lock, flags); > > Please consider to change the new comment into something like the following: > "Before a SCSI command is dispatched, get_device(&sdev->sdev_gendev) is called > and the host, target and device busy counters are increased. Since requeuing a > request causes these actions to be repeated and since scsi_device_unbusy() has > already been called, put_device(&device->sdev_gendev) must still be called. Call > put_device() after blk_mq_requeue_request() to avoid that removal of the SCSI > device can start before requeueing has happened."
Yes, your comment is more detailed and clearly.
Sincerely Jianchao
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