From b6d57317fbf8b2329bbbc3b00fcc47310f72ff2a Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 5 Mar 2020 13:48:22 +0000
Subject: drm/i915: Return early for await_start on same timeline
Git-commit: c951b0af2dddbb1f34be103029eb9030392d5554
Patch-mainline: v5.6-rc6
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Requests within a timeline are ordered by that timeline, so awaiting for
the start of a request within the timeline is a no-op. This used to work
by falling out of the mutex_trylock() as the signaler and waiter had the
same timeline and not returning an error.
Fixes: 6a79d848403d ("drm/i915: Lock signaler timeline while navigating")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: <stable@vger.kernel.org> # v5.5+
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305134822.2750496-1-chris@chris-wilson.co.uk
(cherry picked from commit ab7a69020fb5d5c7ba19fba60f62fd6f9ca9f779)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/i915_request.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 468ca1052bcb..7cd60b4a329b 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -776,8 +776,8 @@ i915_request_await_start(struct i915_request *rq, struct i915_request *signal)
struct dma_fence *fence;
int err;
- GEM_BUG_ON(i915_request_timeline(rq) ==
- rcu_access_pointer(signal->timeline));
+ if (i915_request_timeline(rq) == rcu_access_pointer(signal->timeline))
+ return 0;
if (i915_request_started(signal))
return 0;
--
2.28.0