drm/msm: print offender task name on hangcheck recovery

Track the pid per submit, so we can print the name of the task which
submitted the batch that caused the gpu to hang.
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_gem.h

@@ -86,6 +86,7 @@ struct msm_gem_submit {
 	struct list_head bo_list;
 	struct ww_acquire_ctx ticket;
 	struct fence *fence;
+	struct pid *pid;    /* submitting process */
 	bool valid;         /* true if no cmdstream patching needed */
 	unsigned int nr_cmds;
 	unsigned int nr_bos;

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -45,6 +45,7 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
 
 	submit->dev = dev;
 	submit->gpu = gpu;
+	submit->pid = get_pid(task_pid(current));
 
 	/* initially, until copy_from_user() and bo lookup succeeds: */
 	submit->nr_bos = 0;
@@ -60,6 +61,7 @@ void msm_gem_submit_free(struct msm_gem_submit *submit)
 {
 	fence_put(submit->fence);
 	list_del(&submit->node);
+	put_pid(submit->pid);
 	kfree(submit);
 }
 

drivers/gpu/drm/msm/msm_gpu.c

@@ -272,16 +272,30 @@ static void recover_worker(struct work_struct *work)
 {
 	struct msm_gpu *gpu = container_of(work, struct msm_gpu, recover_work);
 	struct drm_device *dev = gpu->dev;
+	struct msm_gem_submit *submit;
 	uint32_t fence = gpu->funcs->last_fence(gpu);
 
-	dev_err(dev->dev, "%s: hangcheck recover!\n", gpu->name);
-
 	msm_update_fence(gpu->fctx, fence + 1);
 
 	mutex_lock(&dev->struct_mutex);
-	if (msm_gpu_active(gpu)) {
-		struct msm_gem_submit *submit;
 
+	dev_err(dev->dev, "%s: hangcheck recover!\n", gpu->name);
+	list_for_each_entry(submit, &gpu->submit_list, node) {
+		if (submit->fence->seqno == (fence + 1)) {
+			struct task_struct *task;
+
+			rcu_read_lock();
+			task = pid_task(submit->pid, PIDTYPE_PID);
+			if (task) {
+				dev_err(dev->dev, "%s: offending task: %s\n",
+						gpu->name, task->comm);
+			}
+			rcu_read_unlock();
+			break;
+		}
+	}
+
+	if (msm_gpu_active(gpu)) {
 		/* retire completed submits, plus the one that hung: */
 		retire_submits(gpu);
 
@@ -293,6 +307,7 @@ static void recover_worker(struct work_struct *work)
 			gpu->funcs->submit(gpu, submit, NULL);
 		}
 	}
+
 	mutex_unlock(&dev->struct_mutex);
 
 	msm_gpu_retire(gpu);