From aab4707fdd754d4c4f0df718f3c7546b6eb40d20 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 2 Jul 2020 10:52:18 +0100 Subject: [PATCH] drm/i915/gt: Harden the heartbeat against a stuck driver If the driver gets stuck holding the kernel timeline, we cannot issue a heartbeat and so fail to discover that the driver is indeed stuck and do not issue a GPU reset (which would hopefully unstick the driver!). Switch to using a trylock so that we can query if the heartbeat's timeline mutex is locked elsewhere, and then use the timer to probe if it remains stuck at the same spot for consecutive heartbeats, indicating that the mutex has not been released and the engine has not progressed. Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20200702095219.963-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c | 14 ++++++++++++-- drivers/gpu/drm/i915/gt/intel_engine_types.h | 1 + 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c index 8db7e93..1c6c669 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_heartbeat.c @@ -65,6 +65,7 @@ static void heartbeat(struct work_struct *wrk) container_of(wrk, typeof(*engine), heartbeat.work.work); struct intel_context *ce = engine->kernel_context; struct i915_request *rq; + unsigned long serial; /* Just in case everything has gone horribly wrong, give it a kick */ intel_engine_flush_submission(engine); @@ -122,10 +123,19 @@ static void heartbeat(struct work_struct *wrk) goto out; } - if (engine->wakeref_serial == engine->serial) + serial = READ_ONCE(engine->serial); + if (engine->wakeref_serial == serial) goto out; - mutex_lock(&ce->timeline->mutex); + if (!mutex_trylock(&ce->timeline->mutex)) { + /* Unable to lock the kernel timeline, is the engine stuck? */ + if (xchg(&engine->heartbeat.blocked, serial) == serial) + intel_gt_handle_error(engine->gt, engine->mask, + I915_ERROR_CAPTURE, + "no heartbeat on %s", + engine->name); + goto out; + } intel_context_enter(ce); rq = __i915_request_create(ce, GFP_NOWAIT | __GFP_NOWARN); diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h index 073c376..490af81 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h @@ -348,6 +348,7 @@ struct intel_engine_cs { struct { struct delayed_work work; struct i915_request *systole; + unsigned long blocked; } heartbeat; unsigned long serial; -- 2.7.4