* [PATCH] scsi: mq queue stall during command requeue
@ 2017-01-19 14:17 Hannes Reinecke
2017-01-19 14:46 ` Christoph Hellwig
2017-01-19 16:11 ` Bart Van Assche
0 siblings, 2 replies; 7+ messages in thread
From: Hannes Reinecke @ 2017-01-19 14:17 UTC (permalink / raw)
To: Martin K. Petersen
Cc: Christoph Hellwig, James Bottomley, Johannes Thumshirn,
linux-scsi, Hannes Reinecke, Hannes Reinecke
When we're hitting a busy condition in queuecommand() we need to
stop the hardware queue before calling blk_mq_delay_queue(); if
we don't blk_mq_delay_queue() will not do anything and requeue
will never triggered.
Signed-off-by: Hannes Reinecke <hare@suse.com>
---
drivers/scsi/scsi_lib.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index e9e1e14..4b1cbc6 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1951,8 +1951,10 @@ static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
switch (ret) {
case BLK_MQ_RQ_QUEUE_BUSY:
if (atomic_read(&sdev->device_busy) == 0 &&
- !scsi_device_blocked(sdev))
+ !scsi_device_blocked(sdev)) {
+ blk_mq_stop_hw_queue(hctx);
blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
+ }
break;
case BLK_MQ_RQ_QUEUE_ERROR:
/*
--
1.8.5.6
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 14:17 [PATCH] scsi: mq queue stall during command requeue Hannes Reinecke
@ 2017-01-19 14:46 ` Christoph Hellwig
2017-01-19 14:52 ` Hannes Reinecke
2017-01-19 16:11 ` Bart Van Assche
1 sibling, 1 reply; 7+ messages in thread
From: Christoph Hellwig @ 2017-01-19 14:46 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Martin K. Petersen, Christoph Hellwig, James Bottomley,
Johannes Thumshirn, linux-scsi, Hannes Reinecke
On Thu, Jan 19, 2017 at 03:17:45PM +0100, Hannes Reinecke wrote:
> When we're hitting a busy condition in queuecommand() we need to
> stop the hardware queue before calling blk_mq_delay_queue(); if
> we don't blk_mq_delay_queue() will not do anything and requeue
> will never triggered.
I suspect the stop needs to move into blk_mq_delay_queue to make
it more useful.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 14:46 ` Christoph Hellwig
@ 2017-01-19 14:52 ` Hannes Reinecke
2017-01-19 14:58 ` Jens Axboe
0 siblings, 1 reply; 7+ messages in thread
From: Hannes Reinecke @ 2017-01-19 14:52 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Martin K. Petersen, James Bottomley, Johannes Thumshirn,
linux-scsi, Hannes Reinecke, Jens Axboe
On 01/19/2017 03:46 PM, Christoph Hellwig wrote:
> On Thu, Jan 19, 2017 at 03:17:45PM +0100, Hannes Reinecke wrote:
>> When we're hitting a busy condition in queuecommand() we need to
>> stop the hardware queue before calling blk_mq_delay_queue(); if
>> we don't blk_mq_delay_queue() will not do anything and requeue
>> will never triggered.
>
> I suspect the stop needs to move into blk_mq_delay_queue to make
> it more useful.
>
Which is what I've suggested to Jens, too.
And he even agreed to it :-)
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 14:52 ` Hannes Reinecke
@ 2017-01-19 14:58 ` Jens Axboe
2017-01-19 15:12 ` Christoph Hellwig
0 siblings, 1 reply; 7+ messages in thread
From: Jens Axboe @ 2017-01-19 14:58 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig
Cc: Martin K. Petersen, James Bottomley, Johannes Thumshirn,
linux-scsi, Hannes Reinecke, James Smart
On 01/19/2017 06:52 AM, Hannes Reinecke wrote:
> On 01/19/2017 03:46 PM, Christoph Hellwig wrote:
>> On Thu, Jan 19, 2017 at 03:17:45PM +0100, Hannes Reinecke wrote:
>>> When we're hitting a busy condition in queuecommand() we need to
>>> stop the hardware queue before calling blk_mq_delay_queue(); if
>>> we don't blk_mq_delay_queue() will not do anything and requeue
>>> will never triggered.
>>
>> I suspect the stop needs to move into blk_mq_delay_queue to make
>> it more useful.
>>
> Which is what I've suggested to Jens, too.
> And he even agreed to it :-)
Yeah, I made that patch and grepped the tree. The usage in the fc
code in nvme looks weird. It's stopping all potential hardware queues,
yet only delaying one.
if (op->rq) {
blk_mq_stop_hw_queues(op->rq->q);
blk_mq_delay_queue(queue->hctx, NVMEFC_QUEUE_DELAY);
}
return BLK_MQ_RQ_QUEUE_BUSY;
James/Christoph, what's going on there? I'm going to leave that one
as-is for now, but add the stop to the delay. If the above stop-all is
indeed buggy, then it can later just be removed.
--
Jens Axboe
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 14:58 ` Jens Axboe
@ 2017-01-19 15:12 ` Christoph Hellwig
0 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2017-01-19 15:12 UTC (permalink / raw)
To: Jens Axboe
Cc: Hannes Reinecke, Christoph Hellwig, Martin K. Petersen,
James Bottomley, Johannes Thumshirn, linux-scsi, Hannes Reinecke,
James Smart
On Thu, Jan 19, 2017 at 06:58:09AM -0800, Jens Axboe wrote:
> Yeah, I made that patch and grepped the tree. The usage in the fc
> code in nvme looks weird. It's stopping all potential hardware queues,
> yet only delaying one.
>
> if (op->rq) {
> blk_mq_stop_hw_queues(op->rq->q);
> blk_mq_delay_queue(queue->hctx, NVMEFC_QUEUE_DELAY);
> }
> return BLK_MQ_RQ_QUEUE_BUSY;
>
> James/Christoph, what's going on there? I'm going to leave that one
> as-is for now, but add the stop to the delay. If the above stop-all is
> indeed buggy, then it can later just be removed.
It looks broken to me, but I'll need James to confirm.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 14:17 [PATCH] scsi: mq queue stall during command requeue Hannes Reinecke
2017-01-19 14:46 ` Christoph Hellwig
@ 2017-01-19 16:11 ` Bart Van Assche
2017-01-20 7:24 ` Hannes Reinecke
1 sibling, 1 reply; 7+ messages in thread
From: Bart Van Assche @ 2017-01-19 16:11 UTC (permalink / raw)
To: hare, martin.petersen; +Cc: hch, james.bottomley, linux-scsi, jth, hare
On Thu, 2017-01-19 at 15:17 +0100, Hannes Reinecke wrote:
> When we're hitting a busy condition in queuecommand() we need to
> stop the hardware queue before calling blk_mq_delay_queue(); if
> we don't blk_mq_delay_queue() will not do anything and requeue
> will never triggered.
>
> Signed-off-by: Hannes Reinecke <hare@suse.com>
> ---
> drivers/scsi/scsi_lib.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index e9e1e14..4b1cbc6 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1951,8 +1951,10 @@ static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
> switch (ret) {
> case BLK_MQ_RQ_QUEUE_BUSY:
> if (atomic_read(&sdev->device_busy) == 0 &&
> - !scsi_device_blocked(sdev))
> + !scsi_device_blocked(sdev)) {
> + blk_mq_stop_hw_queue(hctx);
> blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
> + }
> break;
> case BLK_MQ_RQ_QUEUE_ERROR:
> /*
You may want to add Fixes: 52d7f1b5c2f3 (blk-mq: Avoid that requeueing
starts stopped queues). See also
https://www.spinics.net/lists/linux-block/msg06144.html.
Bart.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] scsi: mq queue stall during command requeue
2017-01-19 16:11 ` Bart Van Assche
@ 2017-01-20 7:24 ` Hannes Reinecke
0 siblings, 0 replies; 7+ messages in thread
From: Hannes Reinecke @ 2017-01-20 7:24 UTC (permalink / raw)
To: Bart Van Assche, martin.petersen
Cc: hch, james.bottomley, linux-scsi, jth, hare
On 01/19/2017 05:11 PM, Bart Van Assche wrote:
> On Thu, 2017-01-19 at 15:17 +0100, Hannes Reinecke wrote:
>> When we're hitting a busy condition in queuecommand() we need to
>> stop the hardware queue before calling blk_mq_delay_queue(); if
>> we don't blk_mq_delay_queue() will not do anything and requeue
>> will never triggered.
>>
>> Signed-off-by: Hannes Reinecke <hare@suse.com>
>> ---
>> drivers/scsi/scsi_lib.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>> index e9e1e14..4b1cbc6 100644
>> --- a/drivers/scsi/scsi_lib.c
>> +++ b/drivers/scsi/scsi_lib.c
>> @@ -1951,8 +1951,10 @@ static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
>> switch (ret) {
>> case BLK_MQ_RQ_QUEUE_BUSY:
>> if (atomic_read(&sdev->device_busy) == 0 &&
>> - !scsi_device_blocked(sdev))
>> + !scsi_device_blocked(sdev)) {
>> + blk_mq_stop_hw_queue(hctx);
>> blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY);
>> + }
>> break;
>> case BLK_MQ_RQ_QUEUE_ERROR:
>> /*
>
> You may want to add Fixes: 52d7f1b5c2f3 (blk-mq: Avoid that requeueing
> starts stopped queues). See also
> https://www.spinics.net/lists/linux-block/msg06144.html.
>
Yes indeed.
But the powers that be still ponder if it should be fixed in
the SCSI stack or whether it's a generic fix for blk_mq_delay_queue().
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2017-01-20 7:43 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-19 14:17 [PATCH] scsi: mq queue stall during command requeue Hannes Reinecke
2017-01-19 14:46 ` Christoph Hellwig
2017-01-19 14:52 ` Hannes Reinecke
2017-01-19 14:58 ` Jens Axboe
2017-01-19 15:12 ` Christoph Hellwig
2017-01-19 16:11 ` Bart Van Assche
2017-01-20 7:24 ` Hannes Reinecke
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