From f239218209db39856b865ef908a0d269dafdb5d4 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 6 Dec 2019 16:04:26 +0000
Subject: drm/i915: Check for error before calling cmpxchg()
Git-commit: 5e6a94713be051c491cd47c85263661af07b629c
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Only do the locked compare of the existing fence->error if we actually
need to set an error. As we tend to call i915_sw_fence_set_error_once()
unconditionally, it saves on typing to put the common has-error check
into the inline.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191206160428.1503343-1-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/i915_sw_fence.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_sw_fence.h b/drivers/gpu/drm/i915/i915_sw_fence.h
index 1e90d9a51bd2..19e806ce43bc 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.h
+++ b/drivers/gpu/drm/i915/i915_sw_fence.h
@@ -112,7 +112,8 @@ static inline void i915_sw_fence_wait(struct i915_sw_fence *fence)
static inline void
i915_sw_fence_set_error_once(struct i915_sw_fence *fence, int error)
{
- cmpxchg(&fence->error, 0, error);
+ if (unlikely(error))
+ cmpxchg(&fence->error, 0, error);
}
#endif /* _I915_SW_FENCE_H_ */
--
2.28.0