evie/android_kernel_oneplus_msm8998
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Merge "drm/msm: Fix race condition in the submit path"

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Linux Build Service Account 2017-08-03 20:51:29 -07:00 • committed by Gerrit - the friendly Code Review server
commit 17273e1577
2 changed files with 20 additions and 3 deletions
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8
drivers/gpu/drm/msm/adreno/a5xx_gpu.h
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@ -70,6 +70,8 @@ struct a5xx_gpu {
* PREEMPT_NONE - no preemption in progress. Next state START.
* PREEMPT_START - The trigger is evaulating if preemption is possible. Next
* states: TRIGGERED, NONE
* PREEMPT_ABORT - An intermediate state before moving back to NONE. Next
* state: NONE.
* PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next
* states: FAULTED, PENDING
* PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger
@ -81,6 +83,7 @@ struct a5xx_gpu {
enum preempt_state {
PREEMPT_NONE = 0,
PREEMPT_START,
PREEMPT_ABORT,
PREEMPT_TRIGGERED,
PREEMPT_FAULTED,
PREEMPT_PENDING,
@ -184,7 +187,10 @@ int a5xx_snapshot(struct msm_gpu *gpu, struct msm_snapshot *snapshot);
/* Return true if we are in a preempt state */
static inline bool a5xx_in_preempt(struct a5xx_gpu *a5xx_gpu)
{
return !(atomic_read(&a5xx_gpu->preempt_state) == PREEMPT_NONE);
int preempt_state = atomic_read(&a5xx_gpu->preempt_state);
return !(preempt_state == PREEMPT_NONE ||
preempt_state == PREEMPT_ABORT);
}
int a5xx_counters_init(struct adreno_gpu *adreno_gpu);

15
drivers/gpu/drm/msm/adreno/a5xx_preempt.c
View file

@ -128,9 +128,20 @@ void a5xx_preempt_trigger(struct msm_gpu *gpu)
* one do nothing except to update the wptr to the latest and greatest
*/
if (!ring || (a5xx_gpu->cur_ring == ring)) {
update_wptr(gpu, ring);
/*
* Its possible that while a preemption request is in progress
* from an irq context, a user context trying to submit might
* fail to update the write pointer, because it determines
* that the preempt state is not PREEMPT_NONE.
*
* Close the race by introducing an intermediate
* state PREEMPT_ABORT to let the submit path
* know that the ringbuffer is not going to change
* and can safely update the write pointer.
*/
/* Set the state back to NONE */
set_preempt_state(a5xx_gpu, PREEMPT_ABORT);
update_wptr(gpu, a5xx_gpu->cur_ring);
set_preempt_state(a5xx_gpu, PREEMPT_NONE);
return;
}