Re: [PATCH 06/12] blk-mq: Add a kick_requeue_list argument to blk_mq_requeue_request()

[Christoph Hellwig]

On Wed, Oct 26, 2016 at 03:53:39PM -0700, Bart Van Assche wrote:
> Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls
> are followed by kicking the requeue list. Hence add an argument to
> these two functions that allows to kick the requeue list. This was
> proposed by Christoph Hellwig.

Looks good,

Reviewed-by: Christoph Hellwig 
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Re: [PATCH 06/12] blk-mq: Add a kick_requeue_list argument to blk_mq_requeue_request()

[Johannes Thumshirn]

On Wed, Oct 26, 2016 at 03:53:39PM -0700, Bart Van Assche wrote:
> Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls
> are followed by kicking the requeue list. Hence add an argument to
> these two functions that allows to kick the requeue list. This was
> proposed by Christoph Hellwig.
> 
> Signed-off-by: Bart Van Assche 
> Cc: Christoph Hellwig 

Looks good,
Reviewed-by: Johannes Thumshirn 

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Re: [PATCH 06/12] blk-mq: Add a kick_requeue_list argument to blk_mq_requeue_request()

[Hannes Reinecke]

On 10/27/2016 12:53 AM, Bart Van Assche wrote:
> Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls
> are followed by kicking the requeue list. Hence add an argument to
> these two functions that allows to kick the requeue list. This was
> proposed by Christoph Hellwig.
> 
> Signed-off-by: Bart Van Assche 
> Cc: Christoph Hellwig 
> Cc: Hannes Reinecke 
> Cc: Sagi Grimberg 
> Cc: Johannes Thumshirn 
> ---
>  block/blk-flush.c|  5 +
>  block/blk-mq.c   | 10 +++---
>  drivers/block/xen-blkfront.c |  2 +-
>  drivers/md/dm-rq.c   |  2 +-
>  drivers/nvme/host/core.c |  2 +-
>  drivers/scsi/scsi_lib.c  |  4 +---
>  include/linux/blk-mq.h   |  5 +++--
>  7 files changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/block/blk-flush.c b/block/blk-flush.c
> index 6a14b68..a834aed 100644
> --- a/block/blk-flush.c
> +++ b/block/blk-flush.c
> @@ -134,10 +134,7 @@ static void blk_flush_restore_request(struct request *rq)
>  static bool blk_flush_queue_rq(struct request *rq, bool add_front)
>  {
>   if (rq->q->mq_ops) {
> - struct request_queue *q = rq->q;
> -
> - blk_mq_add_to_requeue_list(rq, add_front);
> - blk_mq_kick_requeue_list(q);
> + blk_mq_add_to_requeue_list(rq, add_front, true);
>   return false;
>   } else {
>   if (add_front)
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 4945437..688bcc3 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -492,12 +492,12 @@ static void __blk_mq_requeue_request(struct request *rq)
>   }
>  }
>  
> -void blk_mq_requeue_request(struct request *rq)
> +void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
>  {
>   __blk_mq_requeue_request(rq);
>  
>   BUG_ON(blk_queued_rq(rq));
> - blk_mq_add_to_requeue_list(rq, true);
> + blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
>  }
>  EXPORT_SYMBOL(blk_mq_requeue_request);
>  
> @@ -535,7 +535,8 @@ static void blk_mq_requeue_work(struct work_struct *work)
>   blk_mq_start_hw_queues(q);
>  }
>  
> -void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
> +void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
> + bool kick_requeue_list)
>  {
>   struct request_queue *q = rq->q;
>   unsigned long flags;
> @@ -554,6 +555,9 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool 
> at_head)
>   list_add_tail(>queuelist, >requeue_list);
>   }
>   spin_unlock_irqrestore(>requeue_lock, flags);
> +
> + if (kick_requeue_list)
> + blk_mq_kick_requeue_list(q);
>  }
>  EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
>  
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index 9908597..1ca702d 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -2043,7 +2043,7 @@ static int blkif_recover(struct blkfront_info *info)
>   /* Requeue pending requests (flush or discard) */
>   list_del_init(>queuelist);
>   BUG_ON(req->nr_phys_segments > segs);
> - blk_mq_requeue_request(req);
> + blk_mq_requeue_request(req, false);
>   }
>   blk_mq_kick_requeue_list(info->rq);
>  
> diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
> index dc75bea..fbd37b4 100644
> --- a/drivers/md/dm-rq.c
> +++ b/drivers/md/dm-rq.c
> @@ -354,7 +354,7 @@ EXPORT_SYMBOL(dm_mq_kick_requeue_list);
>  
>  static void dm_mq_delay_requeue_request(struct request *rq, unsigned long 
> msecs)
>  {
> - blk_mq_requeue_request(rq);
> + blk_mq_requeue_request(rq, false);
>   __dm_mq_kick_requeue_list(rq->q, msecs);
>  }
>  
Hmm. __dm_mq_kick_requeue_list() does essentially the same.
Have you checked if you can use 'true' here and drop the call to it?
However, it does take the queue_lock when doing so.
Is that required? None of the other drivers do it ...

Cheers,

Hannes
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h...@suse.de   +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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HRB 21284 (AG Nürnberg)
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[PATCH 06/12] blk-mq: Add a kick_requeue_list argument to blk_mq_requeue_request()

[Bart Van Assche]

Most blk_mq_requeue_request() and blk_mq_add_to_requeue_list() calls
are followed by kicking the requeue list. Hence add an argument to
these two functions that allows to kick the requeue list. This was
proposed by Christoph Hellwig.

Signed-off-by: Bart Van Assche 
Cc: Christoph Hellwig 
Cc: Hannes Reinecke 
Cc: Sagi Grimberg 
Cc: Johannes Thumshirn 
---
 block/blk-flush.c|  5 +
 block/blk-mq.c   | 10 +++---
 drivers/block/xen-blkfront.c |  2 +-
 drivers/md/dm-rq.c   |  2 +-
 drivers/nvme/host/core.c |  2 +-
 drivers/scsi/scsi_lib.c  |  4 +---
 include/linux/blk-mq.h   |  5 +++--
 7 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/block/blk-flush.c b/block/blk-flush.c
index 6a14b68..a834aed 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -134,10 +134,7 @@ static void blk_flush_restore_request(struct request *rq)
 static bool blk_flush_queue_rq(struct request *rq, bool add_front)
 {
if (rq->q->mq_ops) {
-   struct request_queue *q = rq->q;
-
-   blk_mq_add_to_requeue_list(rq, add_front);
-   blk_mq_kick_requeue_list(q);
+   blk_mq_add_to_requeue_list(rq, add_front, true);
return false;
} else {
if (add_front)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4945437..688bcc3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -492,12 +492,12 @@ static void __blk_mq_requeue_request(struct request *rq)
}
 }
 
-void blk_mq_requeue_request(struct request *rq)
+void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
 {
__blk_mq_requeue_request(rq);
 
BUG_ON(blk_queued_rq(rq));
-   blk_mq_add_to_requeue_list(rq, true);
+   blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
 }
 EXPORT_SYMBOL(blk_mq_requeue_request);
 
@@ -535,7 +535,8 @@ static void blk_mq_requeue_work(struct work_struct *work)
blk_mq_start_hw_queues(q);
 }
 
-void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
+void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
+   bool kick_requeue_list)
 {
struct request_queue *q = rq->q;
unsigned long flags;
@@ -554,6 +555,9 @@ void blk_mq_add_to_requeue_list(struct request *rq, bool 
at_head)
list_add_tail(>queuelist, >requeue_list);
}
spin_unlock_irqrestore(>requeue_lock, flags);
+
+   if (kick_requeue_list)
+   blk_mq_kick_requeue_list(q);
 }
 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9908597..1ca702d 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -2043,7 +2043,7 @@ static int blkif_recover(struct blkfront_info *info)
/* Requeue pending requests (flush or discard) */
list_del_init(>queuelist);
BUG_ON(req->nr_phys_segments > segs);
-   blk_mq_requeue_request(req);
+   blk_mq_requeue_request(req, false);
}
blk_mq_kick_requeue_list(info->rq);
 
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index dc75bea..fbd37b4 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -354,7 +354,7 @@ EXPORT_SYMBOL(dm_mq_kick_requeue_list);
 
 static void dm_mq_delay_requeue_request(struct request *rq, unsigned long 
msecs)
 {
-   blk_mq_requeue_request(rq);
+   blk_mq_requeue_request(rq, false);
__dm_mq_kick_requeue_list(rq->q, msecs);
 }
 
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 79e679d..7bb73ba 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -203,7 +203,7 @@ void nvme_requeue_req(struct request *req)
 {
unsigned long flags;
 
-   blk_mq_requeue_request(req);
+   blk_mq_requeue_request(req, false);
spin_lock_irqsave(req->q->queue_lock, flags);
if (!blk_queue_stopped(req->q))
blk_mq_kick_requeue_list(req->q);
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 2cca9cf..ab5b06f 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -86,10 +86,8 @@ scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
 static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
 {
struct scsi_device *sdev = cmd->device;
-   struct request_queue *q = cmd->request->q;
 
-   blk_mq_requeue_request(cmd->request);
-   blk_mq_kick_requeue_list(q);
+   blk_mq_requeue_request(cmd->request, true);
put_device(>sdev_gendev);
 }
 
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 61be48b..76f6319 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -218,8 +218,9 @@ void blk_mq_start_request(struct request *rq);
 void blk_mq_end_request(struct request *rq, int error);
 void __blk_mq_end_request(struct