[PATCH] scsi-mq: Always unprepare before requeuing a request

[PATCH] scsi-mq: Always unprepare before requeuing a request

[Bart Van Assche]

One of the two scsi-mq functions that requeue a request unprepares
a request before requeueing (scsi_io_completion()) but the other
function not (__scsi_queue_insert()). Make sure that a request is
unprepared before requeuing it.

Fixes: commit d285203cf647 ("scsi: add support for a blk-mq based I/O path.")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
---
 drivers/scsi/scsi_lib.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4a2f705cdb14..c7514f3b444a 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -44,6 +44,8 @@ static struct kmem_cache *scsi_sense_cache;
 static struct kmem_cache *scsi_sense_isadma_cache;
 static DEFINE_MUTEX(scsi_sense_cache_mutex);
 
+static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
+
 static inline struct kmem_cache *
 scsi_select_sense_cache(bool unchecked_isa_dma)
 {
@@ -140,6 +142,12 @@ static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
 {
 	struct scsi_device *sdev = cmd->device;
 
+	if (cmd->request->rq_flags & RQF_DONTPREP) {
+		cmd->request->rq_flags &= ~RQF_DONTPREP;
+		scsi_mq_uninit_cmd(cmd);
+	} else {
+		WARN_ON_ONCE(true);
+	}
 	blk_mq_requeue_request(cmd->request, true);
 	put_device(&sdev->sdev_gendev);
 }
@@ -995,8 +1003,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 		 * A new command will be prepared and issued.
 		 */
 		if (q->mq_ops) {
-			cmd->request->rq_flags &= ~RQF_DONTPREP;
-			scsi_mq_uninit_cmd(cmd);
 			scsi_mq_requeue_cmd(cmd);
 		} else {
 			scsi_release_buffers(cmd);
-- 
2.13.3

Re: [PATCH] scsi-mq: Always unprepare before requeuing a request

[Damien Le Moal]

On 8/4/17 06:40, Bart Van Assche wrote:
> One of the two scsi-mq functions that requeue a request unprepares
> a request before requeueing (scsi_io_completion()) but the other
> function not (__scsi_queue_insert()). Make sure that a request is
> unprepared before requeuing it.
> 
> Fixes: commit d285203cf647 ("scsi: add support for a blk-mq based I/O path.")
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Damien Le Moal <damien.lemoal@wdc.com>
> Cc: Johannes Thumshirn <jthumshirn@suse.de>
> Cc: <stable@vger.kernel.org>
> ---
>  drivers/scsi/scsi_lib.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 4a2f705cdb14..c7514f3b444a 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -44,6 +44,8 @@ static struct kmem_cache *scsi_sense_cache;
>  static struct kmem_cache *scsi_sense_isadma_cache;
>  static DEFINE_MUTEX(scsi_sense_cache_mutex);
>  
> +static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
> +
>  static inline struct kmem_cache *
>  scsi_select_sense_cache(bool unchecked_isa_dma)
>  {
> @@ -140,6 +142,12 @@ static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
>  {
>  	struct scsi_device *sdev = cmd->device;
>  
> +	if (cmd->request->rq_flags & RQF_DONTPREP) {
> +		cmd->request->rq_flags &= ~RQF_DONTPREP;
> +		scsi_mq_uninit_cmd(cmd);
> +	} else {
> +		WARN_ON_ONCE(true);
> +	}
>  	blk_mq_requeue_request(cmd->request, true);
>  	put_device(&sdev->sdev_gendev);
>  }
> @@ -995,8 +1003,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
>  		 * A new command will be prepared and issued.
>  		 */
>  		if (q->mq_ops) {
> -			cmd->request->rq_flags &= ~RQF_DONTPREP;
> -			scsi_mq_uninit_cmd(cmd);
>  			scsi_mq_requeue_cmd(cmd);
>  		} else {
>  			scsi_release_buffers(cmd);
> 

Tested-by: Damien Le Moal <damien.lemoal@wdc.com>

This patch is needed for the V2 of the series "Zoned block device
support fixes" that I sent.

Best regards.

-- 
Damien Le Moal,
Western Digital

Re: [PATCH] scsi-mq: Always unprepare before requeuing a request

[Christoph Hellwig]

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] scsi-mq: Always unprepare before requeuing a request

[Johannes Thumshirn]

Thanks Bart,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N�rnberg
GF: Felix Imend�rffer, Jane Smithard, Graham Norton
HRB 21284 (AG N�rnberg)
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Re: [PATCH] scsi-mq: Always unprepare before requeuing a request

[Martin K. Petersen]

Bart,

> One of the two scsi-mq functions that requeue a request unprepares a
> request before requeueing (scsi_io_completion()) but the other
> function not (__scsi_queue_insert()). Make sure that a request is
> unprepared before requeuing it.

Applied to 4.13/scsi-fixes. Thanks much!

-- 
Martin K. Petersen	Oracle Linux Engineering