2022-08-15 16:58:16

by Wenchao Hao

Subject: [PATCH] scsi: increase scsi device's iodone_cnt in scsi_timeout()

The iodone_cnt might be less than iorequest_cnt because
we did not increase the iodone_cnt when a command is done
from timeout.

Signed-off-by: Wenchao Hao <[email protected]>
---
drivers/scsi/scsi_error.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 448748e3fba5..d21ae0090166 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -355,6 +355,7 @@ enum blk_eh_timer_return scsi_timeout(struct request *req)
*/
if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
return BLK_EH_RESET_TIMER;
+ atomic_inc(&scmd->device->iodone_cnt);
if (scsi_abort_command(scmd) != SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT);
scsi_eh_scmd_add(scmd);
--
2.35.3

2022-08-15 16:59:23

by Steffen Maier

Subject: Re: [PATCH] scsi: increase scsi device's iodone_cnt in scsi_timeout()

On 8/15/22 18:43, Wenchao Hao wrote:
> The iodone_cnt might be less than iorequest_cnt because
> we did not increase the iodone_cnt when a command is done
> from timeout.
>
> Signed-off-by: Wenchao Hao <[email protected]>
> ---
> drivers/scsi/scsi_error.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 448748e3fba5..d21ae0090166 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -355,6 +355,7 @@ enum blk_eh_timer_return scsi_timeout(struct request *req)
> */
> if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
> return BLK_EH_RESET_TIMER;
> + atomic_inc(&scmd->device->iodone_cnt);
> if (scsi_abort_command(scmd) != SUCCESS) {
> set_host_byte(scmd, DID_TIME_OUT);
> scsi_eh_scmd_add(scmd);

Not sure, but can't we still get a (late) regular completion even after the
timeout happened (double accounting) and before we successfully aborted the
command?


--
Mit freundlichen Gruessen / Kind regards
Steffen Maier

Linux on IBM Z and LinuxONE

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2022-08-16 07:46:35

by Wenchao Hao

Subject: Re: [PATCH] scsi: increase scsi device's iodone_cnt in scsi_timeout()

On Tue, Aug 16, 2022 at 12:53 AM Steffen Maier <[email protected]> wrote:
>
> On 8/15/22 18:43, Wenchao Hao wrote:
> > The iodone_cnt might be less than iorequest_cnt because
> > we did not increase the iodone_cnt when a command is done
> > from timeout.
> >
> > Signed-off-by: Wenchao Hao <[email protected]>
> > ---
> > drivers/scsi/scsi_error.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> > index 448748e3fba5..d21ae0090166 100644
> > --- a/drivers/scsi/scsi_error.c
> > +++ b/drivers/scsi/scsi_error.c
> > @@ -355,6 +355,7 @@ enum blk_eh_timer_return scsi_timeout(struct request *req)
> > */
> > if (test_and_set_bit(SCMD_STATE_COMPLETE, &scmd->state))
> > return BLK_EH_RESET_TIMER;
> > + atomic_inc(&scmd->device->iodone_cnt);
> > if (scsi_abort_command(scmd) != SUCCESS) {
> > set_host_byte(scmd, DID_TIME_OUT);
> > scsi_eh_scmd_add(scmd);
>
> Not sure, but can't we still get a (late) regular completion even after the
> timeout happened (double accounting) and before we successfully aborted the
> command?
>
>
The flag SCMD_STATE_COMPLETE would take care of it, this would make
sure a scsi command
is done from timeout or regular completion exclusively.

When scsi_abort_command() begins to handle a command, the command
would be finished by
scsi_finish_command() or retried by requeue function.

If a command finished by scsi_finish_command(), it would not add the iodone_cnt.
If a command is requeued, it would call scsi_dispatch_cmd() again and
another iorequest_cnt would be
added.

According to above analysis, I think it's suitable to increase iodone_cnt here.