On finishing the reset, the intention is to restart the GPU before we relinquish the forcewake taken to handle the reset - the goal being the GPU reloads a context before it is allowed to sleep. For this purpose, we used tasklet_flush() which although it accomplished the goal of restarting the GPU, carried with it a sting in its tail: it cleared the TASKLET_STATE_SCHED bit. This meant that if another CPU queued a new request to this engine, we would clear the flag and later attempt to requeue the tasklet on the local CPU, breaking the per-cpu softirq lists. Remove the dangerous tasklet_kill() and just run the tasklet func directly as we know it is safe to do so (the tasklets are internally locked to allow mixed usage from direct submission). Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107710 Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> Cc: Michel Thierry <michel.thierry@xxxxxxxxx> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem.h | 6 ------ drivers/gpu/drm/i915/intel_lrc.c | 17 ++++++----------- 2 files changed, 6 insertions(+), 17 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h index e46592956872..599c4f6eb1ea 100644 --- a/drivers/gpu/drm/i915/i915_gem.h +++ b/drivers/gpu/drm/i915/i915_gem.h @@ -82,12 +82,6 @@ static inline void __tasklet_disable_sync_once(struct tasklet_struct *t) tasklet_unlock_wait(t); } -static inline void __tasklet_enable_sync_once(struct tasklet_struct *t) -{ - if (atomic_dec_return(&t->count) == 0) - tasklet_kill(t); -} - static inline bool __tasklet_is_enabled(const struct tasklet_struct *t) { return !atomic_read(&t->count); diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 36050f085071..f8ceb9c99dd6 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1962,21 +1962,16 @@ static void execlists_reset_finish(struct intel_engine_cs *engine) { struct intel_engine_execlists * const execlists = &engine->execlists; - /* After a GPU reset, we may have requests to replay */ - if (!RB_EMPTY_ROOT(&execlists->queue.rb_root)) - tasklet_schedule(&execlists->tasklet); - /* - * Flush the tasklet while we still have the forcewake to be sure - * that it is not allowed to sleep before we restart and reload a - * context. + * After a GPU reset, we may have requests to replay. Do so now while + * we still have the forcewake to be sure that the GPU is not allowed + * to sleep before we restart and reload a context. * - * As before (with execlists_reset_prepare) we rely on the caller - * serialising multiple attempts to reset so that we know that we - * are the only one manipulating tasklet state. */ - __tasklet_enable_sync_once(&execlists->tasklet); + if (!RB_EMPTY_ROOT(&execlists->queue.rb_root)) + execlists->tasklet.func(execlists->tasklet.data); + tasklet_enable(&execlists->tasklet); GEM_TRACE("%s: depth->%d\n", engine->name, atomic_read(&execlists->tasklet.count)); } -- 2.18.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
