Hi Andrzej,
Thanks for providing your R-b.
On Monday, 21 November 2022 18:40:51 CET Andrzej Hajda wrote:
> On 21.11.2022 15:56, Janusz Krzysztofik wrote:
> > Commit b97060a99b01 ("drm/i915/guc: Update intel_gt_wait_for_idle to work
> > with GuC") extended the API of intel_gt_retire_requests_timeout() with an
> > extra argument 'remaining_timeout', intended for passing back unconsumed
> > portion of requested timeout when 0 (success) is returned. However, when
> > request retirement happens to succeed despite an error returned by a call
> > to dma_fence_wait_timeout(), that error code (a negative value) is passed
> > back instead of remaining time. If we then pass that negative value
> > forward as requested timeout to intel_uc_wait_for_idle(), an explicit BUG
> > will be triggered.
> >
> > If request retirement succeeds but an error code is passed back via
> > remaininig_timeout, we may have no clue on how much of the initial timeout
> > might have been left for spending it on waiting for GuC to become idle.
> > OTOH, since all pending requests have been successfully retired, that
> > error code has been already ignored by intel_gt_retire_requests_timeout(),
> > then we shouldn't fail.
> >
> > Assume no more time has been left on error and pass 0 timeout value to
> > intel_uc_wait_for_idle() to give it a chance to return success if GuC is
> > already idle.
> >
> > v3: Don't fail on any error passed back via remaining_timeout.
> >
> > v2: Fix the issue on the caller side, not the provider.
> >
> > Fixes: b97060a99b01 ("drm/i915/guc: Update intel_gt_wait_for_idle to work
with GuC")
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx # v5.15+
>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
While still open for comments from others, I'm now looking for potential
committer.
Thanks,
Janusz
>
> Regards
> Andrzej
>
> > ---
> > drivers/gpu/drm/i915/gt/intel_gt.c | 9 +++++++--
> > 1 file changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/
intel_gt.c
> > index b5ad9caa55372..7ef0edb2e37cd 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_gt.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_gt.c
> > @@ -677,8 +677,13 @@ int intel_gt_wait_for_idle(struct intel_gt *gt, long
timeout)
> > return -EINTR;
> > }
> >
> > - return timeout ? timeout : intel_uc_wait_for_idle(>->uc,
> > -
remaining_timeout);
> > + if (timeout)
> > + return timeout;
> > +
> > + if (remaining_timeout < 0)
> > + remaining_timeout = 0;
> > +
> > + return intel_uc_wait_for_idle(>->uc, remaining_timeout);
> > }
> >
> > int intel_gt_init(struct intel_gt *gt)
>
>
