1db8c142b6c5 (drm/scheduler: Add drm_sched_suspend/resume_timeout()) made
the job_list_lock IRQ safe in as the suspend/resume calls were expected to
be called from IRQ context. This usage never materialized in upstream.
Instead amdgpu started locking the job_list_lock in an IRQ unsafe way in
amdgpu_ib_preempt_mark_partial_job() and amdgpu_ib_preempt_job_recovery(),
which leads to potential deadlock if one would actually start to call the
drm_sched_suspend/resume_timeout functions from IRQ context.
As no current user needs the locking to be IRQ safe, the local IRQ
disable/enable is pure overhead. Fix the inconsistent locking by changing
all uses of job_list_lock to use the IRQ unsafe locking primitives.
Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/gpu/drm/scheduler/sched_main.c | 38 ++++++++++----------------
1 file changed, 15 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 3c57e84222ca..d1b24444dd99 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -220,8 +220,7 @@ EXPORT_SYMBOL(drm_sched_fault);
*
* Suspend the delayed work timeout for the scheduler. This is done by
* modifying the delayed work timeout to an arbitrary large value,
- * MAX_SCHEDULE_TIMEOUT in this case. Note that this function can be
- * called from an IRQ context.
+ * MAX_SCHEDULE_TIMEOUT in this case.
*
* Returns the timeout remaining
*
@@ -250,43 +249,39 @@ EXPORT_SYMBOL(drm_sched_suspend_timeout);
* @sched: scheduler instance for which to resume the timeout
* @remaining: remaining timeout
*
- * Resume the delayed work timeout for the scheduler. Note that
- * this function can be called from an IRQ context.
+ * Resume the delayed work timeout for the scheduler.
*/
void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched,
unsigned long remaining)
{
- unsigned long flags;
-
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
if (list_empty(&sched->ring_mirror_list))
cancel_delayed_work(&sched->work_tdr);
else
mod_delayed_work(system_wq, &sched->work_tdr, remaining);
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
}
EXPORT_SYMBOL(drm_sched_resume_timeout);
static void drm_sched_job_begin(struct drm_sched_job *s_job)
{
struct drm_gpu_scheduler *sched = s_job->sched;
- unsigned long flags;
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
list_add_tail(&s_job->node, &sched->ring_mirror_list);
drm_sched_start_timeout(sched);
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
}
static void drm_sched_job_timedout(struct work_struct *work)
{
struct drm_gpu_scheduler *sched;
struct drm_sched_job *job;
- unsigned long flags;
sched = container_of(work, struct drm_gpu_scheduler, work_tdr.work);
+
job = list_first_entry_or_null(&sched->ring_mirror_list,
struct drm_sched_job, node);
@@ -303,9 +298,9 @@ static void drm_sched_job_timedout(struct work_struct *work)
}
}
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
drm_sched_start_timeout(sched);
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
}
/**
@@ -368,7 +363,6 @@ EXPORT_SYMBOL(drm_sched_increase_karma);
void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
{
struct drm_sched_job *s_job, *tmp;
- unsigned long flags;
kthread_park(sched->thread);
@@ -388,9 +382,9 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
* remove job from ring_mirror_list.
* Locking here is for concurrent resume timeout
*/
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
list_del_init(&s_job->node);
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
/*
* Wait for job's HW fence callback to finish using s_job
@@ -433,7 +427,6 @@ EXPORT_SYMBOL(drm_sched_stop);
void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
{
struct drm_sched_job *s_job, *tmp;
- unsigned long flags;
int r;
/*
@@ -462,9 +455,9 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
}
if (full_recovery) {
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
drm_sched_start_timeout(sched);
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
}
kthread_unpark(sched->thread);
@@ -648,7 +641,6 @@ static struct drm_sched_job *
drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
{
struct drm_sched_job *job;
- unsigned long flags;
/*
* Don't destroy jobs while the timeout worker is running OR thread
@@ -659,7 +651,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
__kthread_should_park(sched->thread))
return NULL;
- spin_lock_irqsave(&sched->job_list_lock, flags);
+ spin_lock(&sched->job_list_lock);
job = list_first_entry_or_null(&sched->ring_mirror_list,
struct drm_sched_job, node);
@@ -673,7 +665,7 @@ drm_sched_get_cleanup_job(struct drm_gpu_scheduler *sched)
drm_sched_start_timeout(sched);
}
- spin_unlock_irqrestore(&sched->job_list_lock, flags);
+ spin_unlock(&sched->job_list_lock);
return job;
}
--
2.20.1
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