On 21.11.2022 09:30, Janusz Krzysztofik wrote:
Hi Nimroy,
Thanks for looking at this.
On Friday, 18 November 2022 20:56:50 CET Das, Nirmoy wrote:
On 11/18/2022 11:42 AM, Janusz Krzysztofik wrote:
Users of intel_gt_retire_requests_timeout() expect 0 return value on
success. However, we have no protection from passing back 0 potentially
returned by a call to dma_fence_wait_timeout() when it succedes right
after its timeout has expired.
Replace 0 with -ETIME before potentially using the timeout value as return
code, so -ETIME is returned if there are still some requests not retired
after timeout, 0 otherwise.
v2: Move the added lines down so flush_submission() is not affected.
Fixes: f33a8a51602c ("drm/i915: Merge wait_for_timelines with
retire_request")
Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.5+
---
drivers/gpu/drm/i915/gt/intel_gt_requests.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_requests.c b/drivers/gpu/
drm/i915/gt/intel_gt_requests.c
index edb881d756309..3ac4603eeb4ee 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_requests.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_requests.c
@@ -199,6 +199,9 @@ out_active: spin_lock(&timelines->lock);
if (remaining_timeout)
*remaining_timeout = timeout;
+ if (!timeout)
+ timeout = -ETIME;
This will return error, -ETIME when 0 timeout is passed,
intel_gt_retire_requests().
Yes, but only when active_count is not 0 after we loop through
timelines->active_list calling retire_requests() on each and counting up
failures in active_count.
Moving this line just after the call to dma_fence_wait_timeout should
solve the controversy.
Regards
Andrzej
We don't want that.
When 0 timeout is passed to intel_gt_retire_requests(), do we really want it
to return 0 unconditionally, or are we rather interested if those calls to
retire_requests() succeeded?
I think you can use a separate variable to store
return val from the dma_fence_wait_timeout()
Regards,
Nirmoy
+
return active_count ? timeout : 0;
If active count is 0, we return 0 regardless of timeout value, and that's OK.
However, if active_count is not 0, we shouldn't return 0, I believe, we should
return either remaining time if some left, or error (-ETIME) if not. If you
think I'm wrong, please explain why.
Thanks,
Janusz
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