[PATCH 1/4] drm/msm: Fix improper uses of smp_mb__{before,after}_atomic()

[Andrea Parri]

These barriers only apply to the read-modify-write operations; in
particular, they do not apply to the atomic_set() primitive.

Replace the barriers with smp_mb()s.

Fixes: b1fc2839d2f92 ("drm/msm: Implement preemption for A5XX targets")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx>
Reported-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrea Parri <andrea.parri@xxxxxxxxxxxxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Sean Paul <sean@xxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
Cc: linux-arm-msm@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: freedreno@xxxxxxxxxxxxxxxxxxxxx
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/adreno/a5xx_preempt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
index 3d62310a535fb..ee0820ee0c664 100644
--- a/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
+++ b/drivers/gpu/drm/msm/adreno/a5xx_preempt.c
@@ -39,10 +39,10 @@ static inline void set_preempt_state(struct a5xx_gpu *gpu,
 	 * preemption or in the interrupt handler so barriers are needed
 	 * before...
 	 */
-	smp_mb__before_atomic();
+	smp_mb();
 	atomic_set(&gpu->preempt_state, new);
 	/* ... and after*/
-	smp_mb__after_atomic();
+	smp_mb();
 }
 
 /* Write the most recent wptr for the given ring into the hardware */
-- 
2.7.4