Now that we can pass our own workqueue to drm_sched_init(), we can use an ordered workqueue on for both the scheduler timeout tdr and our own reset work (which we use when the reset is not caused by a fault/timeout on a specific job, like when we have AS_ACTIVE bit stuck). This guarantees that the timeout handlers and reset handler can't run concurrently which drastically simplifies the locking.
v5: * Don't call cancel_delayed_timeout() in the reset path (those works are canceled in drm_sched_stop())
v4: * Actually pass the reset workqueue to drm_sched_init() * Don't call cancel_work_sync() in panfrost_reset(). It will deadlock since it might be called from the reset work, which is executing and cancel_work_sync() will wait for the handler to return. Checking the reset pending status should avoid spurious resets
v3: * New patch
Suggested-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Boris Brezillon boris.brezillon@collabora.com Reviewed-by: Steven Price steven.price@arm.com --- drivers/gpu/drm/panfrost/panfrost_device.h | 6 +- drivers/gpu/drm/panfrost/panfrost_job.c | 186 ++++++++------------- 2 files changed, 69 insertions(+), 123 deletions(-)
diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h index aec11b6f5abc..d37bc09809e8 100644 --- a/drivers/gpu/drm/panfrost/panfrost_device.h +++ b/drivers/gpu/drm/panfrost/panfrost_device.h @@ -109,6 +109,7 @@ struct panfrost_device { struct mutex sched_lock;
struct { + struct workqueue_struct *wq; struct work_struct work; atomic_t pending; } reset; @@ -247,9 +248,8 @@ const char *panfrost_exception_name(u32 exception_code); static inline void panfrost_device_schedule_reset(struct panfrost_device *pfdev) { - /* Schedule a reset if there's no reset in progress. */ - if (!atomic_xchg(&pfdev->reset.pending, 1)) - schedule_work(&pfdev->reset.work); + atomic_set(&pfdev->reset.pending, 1); + queue_work(pfdev->reset.wq, &pfdev->reset.work); }
#endif diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c index 6149e4c7133f..59c23c91e47c 100644 --- a/drivers/gpu/drm/panfrost/panfrost_job.c +++ b/drivers/gpu/drm/panfrost/panfrost_job.c @@ -25,17 +25,8 @@ #define job_write(dev, reg, data) writel(data, dev->iomem + (reg)) #define job_read(dev, reg) readl(dev->iomem + (reg))
-enum panfrost_queue_status { - PANFROST_QUEUE_STATUS_ACTIVE, - PANFROST_QUEUE_STATUS_STOPPED, - PANFROST_QUEUE_STATUS_STARTING, - PANFROST_QUEUE_STATUS_FAULT_PENDING, -}; - struct panfrost_queue_state { struct drm_gpu_scheduler sched; - atomic_t status; - struct mutex lock; u64 fence_context; u64 emit_seqno; }; @@ -368,57 +359,67 @@ void panfrost_job_enable_interrupts(struct panfrost_device *pfdev) job_write(pfdev, JOB_INT_MASK, irq_mask); }
-static bool panfrost_scheduler_stop(struct panfrost_queue_state *queue, - struct drm_sched_job *bad) +static void panfrost_reset(struct panfrost_device *pfdev, + struct drm_sched_job *bad) { - enum panfrost_queue_status old_status; - bool stopped = false; + unsigned int i; + bool cookie;
- mutex_lock(&queue->lock); - old_status = atomic_xchg(&queue->status, - PANFROST_QUEUE_STATUS_STOPPED); - if (old_status == PANFROST_QUEUE_STATUS_STOPPED) - goto out; + if (!atomic_read(&pfdev->reset.pending)) + return; + + /* Stop the schedulers. + * + * FIXME: We temporarily get out of the dma_fence_signalling section + * because the cleanup path generate lockdep splats when taking locks + * to release job resources. We should rework the code to follow this + * pattern: + * + * try_lock + * if (locked) + * release + * else + * schedule_work_to_release_later + */ + for (i = 0; i < NUM_JOB_SLOTS; i++) + drm_sched_stop(&pfdev->js->queue[i].sched, bad); + + cookie = dma_fence_begin_signalling();
- WARN_ON(old_status != PANFROST_QUEUE_STATUS_ACTIVE); - drm_sched_stop(&queue->sched, bad); if (bad) drm_sched_increase_karma(bad);
- stopped = true; + spin_lock(&pfdev->js->job_lock); + for (i = 0; i < NUM_JOB_SLOTS; i++) { + if (pfdev->jobs[i]) { + pm_runtime_put_noidle(pfdev->dev); + panfrost_devfreq_record_idle(&pfdev->pfdevfreq); + pfdev->jobs[i] = NULL; + } + } + spin_unlock(&pfdev->js->job_lock);
- /* - * Set the timeout to max so the timer doesn't get started - * when we return from the timeout handler (restored in - * panfrost_scheduler_start()). + panfrost_device_reset(pfdev); + + /* GPU has been reset, we can clear the reset pending bit. */ + atomic_set(&pfdev->reset.pending, 0); + + /* Now resubmit jobs that were previously queued but didn't have a + * chance to finish. + * FIXME: We temporarily get out of the DMA fence signalling section + * while resubmitting jobs because the job submission logic will + * allocate memory with the GFP_KERNEL flag which can trigger memory + * reclaim and exposes a lock ordering issue. */ - queue->sched.timeout = MAX_SCHEDULE_TIMEOUT; + dma_fence_end_signalling(cookie); + for (i = 0; i < NUM_JOB_SLOTS; i++) + drm_sched_resubmit_jobs(&pfdev->js->queue[i].sched); + cookie = dma_fence_begin_signalling();
-out: - mutex_unlock(&queue->lock); + for (i = 0; i < NUM_JOB_SLOTS; i++) + drm_sched_start(&pfdev->js->queue[i].sched, true);
- return stopped; -} - -static void panfrost_scheduler_start(struct panfrost_queue_state *queue) -{ - enum panfrost_queue_status old_status; - - mutex_lock(&queue->lock); - old_status = atomic_xchg(&queue->status, - PANFROST_QUEUE_STATUS_STARTING); - WARN_ON(old_status != PANFROST_QUEUE_STATUS_STOPPED); - - /* Restore the original timeout before starting the scheduler. */ - queue->sched.timeout = msecs_to_jiffies(JOB_TIMEOUT_MS); - drm_sched_resubmit_jobs(&queue->sched); - drm_sched_start(&queue->sched, true); - old_status = atomic_xchg(&queue->status, - PANFROST_QUEUE_STATUS_ACTIVE); - if (old_status == PANFROST_QUEUE_STATUS_FAULT_PENDING) - drm_sched_fault(&queue->sched); - - mutex_unlock(&queue->lock); + dma_fence_end_signalling(cookie); }
static enum drm_gpu_sched_stat panfrost_job_timedout(struct drm_sched_job @@ -443,11 +444,8 @@ static enum drm_gpu_sched_stat panfrost_job_timedout(struct drm_sched_job job_read(pfdev, JS_TAIL_LO(js)), sched_job);
- /* Scheduler is already stopped, nothing to do. */ - if (!panfrost_scheduler_stop(&pfdev->js->queue[js], sched_job)) - return DRM_GPU_SCHED_STAT_NOMINAL; - - panfrost_device_schedule_reset(pfdev); + atomic_set(&pfdev->reset.pending, 1); + panfrost_reset(pfdev, sched_job);
return DRM_GPU_SCHED_STAT_NOMINAL; } @@ -474,8 +472,6 @@ static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status) job_write(pfdev, JOB_INT_CLEAR, mask);
if (status & JOB_INT_MASK_ERR(j)) { - enum panfrost_queue_status old_status; - job_write(pfdev, JS_COMMAND_NEXT(j), JS_COMMAND_NOP);
dev_err(pfdev->dev, "js fault, js=%d, status=%s, head=0x%x, tail=0x%x", @@ -483,19 +479,7 @@ static void panfrost_job_handle_irq(struct panfrost_device *pfdev, u32 status) panfrost_exception_name(job_read(pfdev, JS_STATUS(j))), job_read(pfdev, JS_HEAD_LO(j)), job_read(pfdev, JS_TAIL_LO(j))); - - /* - * When the queue is being restarted we don't report - * faults directly to avoid races between the timeout - * and reset handlers. panfrost_scheduler_start() will - * call drm_sched_fault() after the queue has been - * started if status == FAULT_PENDING. - */ - old_status = atomic_cmpxchg(&pfdev->js->queue[j].status, - PANFROST_QUEUE_STATUS_STARTING, - PANFROST_QUEUE_STATUS_FAULT_PENDING); - if (old_status == PANFROST_QUEUE_STATUS_ACTIVE) - drm_sched_fault(&pfdev->js->queue[j].sched); + drm_sched_fault(&pfdev->js->queue[j].sched); }
if (status & JOB_INT_MASK_DONE(j)) { @@ -550,56 +534,13 @@ static irqreturn_t panfrost_job_irq_handler(int irq, void *data) return IRQ_WAKE_THREAD; }
-static void panfrost_reset(struct work_struct *work) +static void panfrost_reset_work(struct work_struct *work) { struct panfrost_device *pfdev = container_of(work, struct panfrost_device, reset.work); - unsigned int i; - bool cookie;
- cookie = dma_fence_begin_signalling(); - for (i = 0; i < NUM_JOB_SLOTS; i++) { - /* - * We want pending timeouts to be handled before we attempt - * to stop the scheduler. If we don't do that and the timeout - * handler is in flight, it might have removed the bad job - * from the list, and we'll lose this job if the reset handler - * enters the critical section in panfrost_scheduler_stop() - * before the timeout handler. - * - * Timeout is set to MAX_SCHEDULE_TIMEOUT - 1 because we need - * something big enough to make sure the timer will not expire - * before we manage to stop the scheduler, but we can't use - * MAX_SCHEDULE_TIMEOUT because drm_sched_get_cleanup_job() - * considers that as 'timer is not running' and will dequeue - * the job without making sure the timeout handler is not - * running. - */ - pfdev->js->queue[i].sched.timeout = MAX_SCHEDULE_TIMEOUT - 1; - cancel_delayed_work_sync(&pfdev->js->queue[i].sched.work_tdr); - panfrost_scheduler_stop(&pfdev->js->queue[i], NULL); - } - - /* All timers have been stopped, we can safely reset the pending state. */ - atomic_set(&pfdev->reset.pending, 0); - - spin_lock(&pfdev->js->job_lock); - for (i = 0; i < NUM_JOB_SLOTS; i++) { - if (pfdev->jobs[i]) { - pm_runtime_put_noidle(pfdev->dev); - panfrost_devfreq_record_idle(&pfdev->pfdevfreq); - pfdev->jobs[i] = NULL; - } - } - spin_unlock(&pfdev->js->job_lock); - - panfrost_device_reset(pfdev); - - for (i = 0; i < NUM_JOB_SLOTS; i++) - panfrost_scheduler_start(&pfdev->js->queue[i]); - - dma_fence_end_signalling(cookie); + panfrost_reset(pfdev, NULL); }
int panfrost_job_init(struct panfrost_device *pfdev) @@ -607,7 +548,7 @@ int panfrost_job_init(struct panfrost_device *pfdev) struct panfrost_job_slot *js; int ret, j, irq;
- INIT_WORK(&pfdev->reset.work, panfrost_reset); + INIT_WORK(&pfdev->reset.work, panfrost_reset_work);
pfdev->js = js = devm_kzalloc(pfdev->dev, sizeof(*js), GFP_KERNEL); if (!js) @@ -629,15 +570,18 @@ int panfrost_job_init(struct panfrost_device *pfdev) return ret; }
- for (j = 0; j < NUM_JOB_SLOTS; j++) { - mutex_init(&js->queue[j].lock); + pfdev->reset.wq = alloc_ordered_workqueue("panfrost-reset", 0); + if (!pfdev->reset.wq) + return -ENOMEM;
+ for (j = 0; j < NUM_JOB_SLOTS; j++) { js->queue[j].fence_context = dma_fence_context_alloc(1);
ret = drm_sched_init(&js->queue[j].sched, &panfrost_sched_ops, 1, 0, - msecs_to_jiffies(JOB_TIMEOUT_MS), NULL, + msecs_to_jiffies(JOB_TIMEOUT_MS), + pfdev->reset.wq, NULL, "pan_js"); if (ret) { dev_err(pfdev->dev, "Failed to create scheduler: %d.", ret); @@ -653,6 +597,7 @@ int panfrost_job_init(struct panfrost_device *pfdev) for (j--; j >= 0; j--) drm_sched_fini(&js->queue[j].sched);
+ destroy_workqueue(pfdev->reset.wq); return ret; }
@@ -665,9 +610,10 @@ void panfrost_job_fini(struct panfrost_device *pfdev)
for (j = 0; j < NUM_JOB_SLOTS; j++) { drm_sched_fini(&js->queue[j].sched); - mutex_destroy(&js->queue[j].lock); }
+ cancel_work_sync(&pfdev->reset.work); + destroy_workqueue(pfdev->reset.wq); }
int panfrost_job_open(struct panfrost_file_priv *panfrost_priv)