[CI,1/5] drm/i915: Remove tasklet flush before disable

Commit Message

Chris Wilson May 16, 2018, 3:30 p.m. UTC

The idea was to try and let the existing tasklet run to completion
before we began the reset, but it involves a racy check against anything
else that tries to run the tasklet. Rather than acknowledge and ignore
the race, let it be and don't try and be too clever.

The tasklet will resume execution after reset (after spinning a bit
during reset), but before we allow it to resume we will have cleared all
the pending state.

Signed-off-by: Chris Wilson <[e-mail]>
Cc: Mika Kuoppala <[e-mail]>
Reviewed-by: Mika Kuoppala <[e-mail]>
---
 drivers/gpu/drm/i915/i915_gem.c | 9 ---------
 1 file changed, 9 deletions(-)

Comments

Chris Wilson May 16, 2018, 3:33 p.m. UTC | #1

Quoting Chris Wilson (2018-05-16 16:30:13)
> The idea was to try and let the existing tasklet run to completion
> before we began the reset, but it involves a racy check against anything
> else that tries to run the tasklet. Rather than acknowledge and ignore
> the race, let it be and don't try and be too clever.
> 
> The tasklet will resume execution after reset (after spinning a bit
> during reset), but before we allow it to resume we will have cleared all
> the pending state.
> 
> Signed-off-by: Chris Wilson <[e-mail]>
> Cc: Mika Kuoppala <[e-mail]>
> Reviewed-by: Mika Kuoppala <[e-mail]>

Apologies for the noise, accidentally squashed a patch during rebasing
and need to recover it for CI.
-Chris

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0a2070112b66..0dc369a9ec4d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3035,16 +3035,7 @@  i915_gem_reset_prepare_engine(struct intel_engine_cs *engine)
 	 * calling engine->init_hw() and also writing the ELSP.
 	 * Turning off the execlists->tasklet until the reset is over
 	 * prevents the race.
-	 *
-	 * Note that this needs to be a single atomic operation on the
-	 * tasklet (flush existing tasks, prevent new tasks) to prevent
-	 * a race between reset and set-wedged. It is not, so we do the best
-	 * we can atm and make sure we don't lock the machine up in the more
-	 * common case of recursively being called from set-wedged from inside
-	 * i915_reset.
 	 */
-	if (!atomic_read(&engine->execlists.tasklet.count))
-		tasklet_kill(&engine->execlists.tasklet);
 	tasklet_disable(&engine->execlists.tasklet);
 
 	/*