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 <[e-mail]>

drivers/gpu/drm/msm/msm_gem.h

···
 	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

···
 
 	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;
···
 {
 	fence_put(submit->fence);
 	list_del(&submit->node);
+	put_pid(submit->pid);
 	kfree(submit);
 }
 

drivers/gpu/drm/msm/msm_gpu.c

···
 {
 	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);
 
···
 			gpu->funcs->submit(gpu, submit, NULL);
 		}
 	}
+
 	mutex_unlock(&dev->struct_mutex);
 
 	msm_gpu_retire(gpu);