On Fri, 2016-04-01 at 15:13 -0400, Joe Lawrence wrote:
> On 04/01/2016 02:51 PM, Ewan D. Milne wrote:
> > On Fri, 2016-04-01 at 13:56 -0400, Joe Lawrence wrote:
> >> @@ -2804,12 +2803,12 @@ _scsih_fw_event_cleanup_queue(struct MPT3SAS_ADAPTER *ioc)
> >> /*
> >> * Wait on the fw_event to complete. If this returns 1, then
> >> * the event was never executed, and we need a put for the
> >> - * reference the delayed_work had on the fw_event.
> >> + * reference the work had on the fw_event.
> >> *
> >> * If it did execute, we wait for it to finish, and the put will
> >> * happen from _firmware_event_work()
> >> */
> >> - if (cancel_delayed_work_sync(&fw_event->delayed_work))
> >> + if (cancel_work_sync(&fw_event->work))
> >> fw_event_work_put(fw_event);
> >>
> >> fw_event_work_put(fw_event);
> >
> > Hmm... Fixes: 146b16c8 (mpt3sas: Refcount fw_events and fix unsafe list usage)
>
> This could technically go back to f92363d12359 (mpt3sas: add new driver
> supporting 12GB SAS) ... but will probably only apply cleanly to
> _scsih_fw_event_cleanup_queue after 146b16c8 (mpt3sas: Refcount
> fw_events and fix unsafe list usage), so you're right.
>
> > Since mpt3sas uses ->work instead of _delayed_work this would seem to be
> > correct, however the deprecated mpt2sas driver had a commit that changed
> > the firmware event work mechanism to use ->delayed_work instead of ->work:
> >
> > commit f1c35e6aea579d5bdb6dc02dfa99c67c7c3b3f67
> > Author: Kashyap, Desai <kashyap.desai@xxxxxxx>
> > Date: Tue Mar 9 16:31:43 2010 +0530
>
> Okay, so this is pre-mpt3sas split.
>
> > [SCSI] mpt2sas: RESCAN Barrier work is added in case of HBA reset.
> >
> > Add the cancel_pending_work flag from the fw_event_work structure, and then to
> > set the flag during host reset, check the flag later from work threads
> > context and if cancel_pending_work_flag is set ingore those events.
>
> More unused mpt2 vestiges in the mpt3 version?
>
> % cd drivers/scsi/mpt3sas/
> % grep 'cancel_pending_work' *.{c,h}
> mpt3sas_scsih.c: * @cancel_pending_work: flag set during reset handling
> mpt3sas_scsih.c: u8 cancel_pending_work;
>
> > Now Rescan after host reset is changed.
> > Added special task MPT2SAS_RESCAN_AFTER_HOST_RESET. This task will be queued
> > at the time of HBA reset. this task is treated as barrier. All work after
> > MPT2SAS_RESCAN_AFTER_HOST_RESET will be treated as new work and will be
> > server by callback handle. If host_recovery is going on while running RESCAN
> > task, it will wait for shos_recovery_done completion which will be called
> > from HBA reset DONE context.
>
> FWIW, I don't see anything like this in today's mpt3sas driver.
Well, that's the question. Is there some functionality missing? Were
the changes abandoned/replaced? mpt2sas used delayed_work for something
else, so maybe that's why the firmware event changes initially used it
(albeit with a 0 delay) but it's hard to know...
cancel_delayed_work() will call del_timer() on delayed_work->timer, but
it looks like kzalloc is used to allocate the fw_event_work objects so
perhaps nothing bad will happen. I was wondering, though, because I
have seen dumps of hung systems with requests that should have timed out
but are not on any timer list.
-Ewan
>
> Regards,
>
> -- Joe
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