drm/amdkfd: don't use dqm lock during device reset/suspend/resume

If device reset/suspend/resume failed for some reason, dqm lock is
hold forever and this causes deadlock. Below is a kernel backtrace when
application open kfd after suspend/resume failed.

Instead of holding dqm lock in pre_reset and releasing dqm lock in
post_reset, add dqm->sched_running flag which is modified in
dqm->ops.start and dqm->ops.stop. The flag doesn't need lock protection
because write/read are all inside dqm lock.

For HWS case, map_queues_cpsch and unmap_queues_cpsch checks
sched_running flag before sending the updated runlist.

v2: For no-HWS case, when device is stopped, don't call
load/destroy_mqd for eviction, restore and create queue, and avoid
debugfs dump hdqs.

Backtrace of dqm lock deadlock:

[Thu Oct 17 16:43:37 2019] INFO: task rocminfo:3024 blocked for more
than 120 seconds.
[Thu Oct 17 16:43:37 2019]       Not tainted
5.0.0-rc1-kfd-compute-rocm-dkms-no-npi-1131 #1
[Thu Oct 17 16:43:37 2019] "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
[Thu Oct 17 16:43:37 2019] rocminfo        D    0  3024   2947
0x80000000
[Thu Oct 17 16:43:37 2019] Call Trace:
[Thu Oct 17 16:43:37 2019]  ? __schedule+0x3d9/0x8a0
[Thu Oct 17 16:43:37 2019]  schedule+0x32/0x70
[Thu Oct 17 16:43:37 2019]  schedule_preempt_disabled+0xa/0x10
[Thu Oct 17 16:43:37 2019]  __mutex_lock.isra.9+0x1e3/0x4e0
[Thu Oct 17 16:43:37 2019]  ? __call_srcu+0x264/0x3b0
[Thu Oct 17 16:43:37 2019]  ? process_termination_cpsch+0x24/0x2f0
[amdgpu]
[Thu Oct 17 16:43:37 2019]  process_termination_cpsch+0x24/0x2f0
[amdgpu]
[Thu Oct 17 16:43:37 2019]
kfd_process_dequeue_from_all_devices+0x42/0x60 [amdgpu]
[Thu Oct 17 16:43:37 2019]  kfd_process_notifier_release+0x1be/0x220
[amdgpu]
[Thu Oct 17 16:43:37 2019]  __mmu_notifier_release+0x3e/0xc0
[Thu Oct 17 16:43:37 2019]  exit_mmap+0x160/0x1a0
[Thu Oct 17 16:43:37 2019]  ? __handle_mm_fault+0xba3/0x1200
[Thu Oct 17 16:43:37 2019]  ? exit_robust_list+0x5a/0x110
[Thu Oct 17 16:43:37 2019]  mmput+0x4a/0x120
[Thu Oct 17 16:43:37 2019]  do_exit+0x284/0xb20
[Thu Oct 17 16:43:37 2019]  ? handle_mm_fault+0xfa/0x200
[Thu Oct 17 16:43:37 2019]  do_group_exit+0x3a/0xa0
[Thu Oct 17 16:43:37 2019]  __x64_sys_exit_group+0x14/0x20
[Thu Oct 17 16:43:37 2019]  do_syscall_64+0x4f/0x100
[Thu Oct 17 16:43:37 2019]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
Suggested-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_device.c

@@ -730,9 +730,6 @@ int kgd2kfd_pre_reset(struct kfd_dev *kfd)
 		return 0;
 	kgd2kfd_suspend(kfd);
 
-	/* hold dqm->lock to prevent further execution*/
-	dqm_lock(kfd->dqm);
-
 	kfd_signal_reset_event(kfd);
 	return 0;
 }
@@ -750,8 +747,6 @@ int kgd2kfd_post_reset(struct kfd_dev *kfd)
 	if (!kfd->init_complete)
 		return 0;
 
-	dqm_unlock(kfd->dqm);
-
 	ret = kfd_resume(kfd);
 	if (ret)
 		return ret;

drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c

@@ -340,6 +340,10 @@ static int create_queue_nocpsch(struct device_queue_manager *dqm,
 	mqd_mgr->init_mqd(mqd_mgr, &q->mqd, q->mqd_mem_obj,
 				&q->gart_mqd_addr, &q->properties);
 	if (q->properties.is_active) {
+		if (!dqm->sched_running) {
+			WARN_ONCE(1, "Load non-HWS mqd while stopped\n");
+			goto add_queue_to_list;
+		}
 
 		if (WARN(q->process->mm != current->mm,
 					"should only run in user thread"))
@@ -351,6 +355,7 @@ static int create_queue_nocpsch(struct device_queue_manager *dqm,
 			goto out_free_mqd;
 	}
 
+add_queue_to_list:
 	list_add(&q->list, &qpd->queues_list);
 	qpd->queue_count++;
 	if (q->properties.is_active)
@@ -458,6 +463,11 @@ static int destroy_queue_nocpsch_locked(struct device_queue_manager *dqm,
 
 	deallocate_doorbell(qpd, q);
 
+	if (!dqm->sched_running) {
+		WARN_ONCE(1, "Destroy non-HWS queue while stopped\n");
+		return 0;
+	}
+
 	retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
 				KFD_PREEMPT_TYPE_WAVEFRONT_RESET,
 				KFD_UNMAP_LATENCY_MS,
@@ -533,6 +543,12 @@ static int update_queue(struct device_queue_manager *dqm, struct queue *q)
 		   (q->properties.type == KFD_QUEUE_TYPE_COMPUTE ||
 		    q->properties.type == KFD_QUEUE_TYPE_SDMA ||
 		    q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI)) {
+
+		if (!dqm->sched_running) {
+			WARN_ONCE(1, "Update non-HWS queue while stopped\n");
+			goto out_unlock;
+		}
+
 		retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
 				KFD_PREEMPT_TYPE_WAVEFRONT_DRAIN,
 				KFD_UNMAP_LATENCY_MS, q->pipe, q->queue);
@@ -602,6 +618,11 @@ static int evict_process_queues_nocpsch(struct device_queue_manager *dqm,
 		mqd_mgr = dqm->mqd_mgrs[get_mqd_type_from_queue_type(
 				q->properties.type)];
 		q->properties.is_active = false;
+		dqm->queue_count--;
+
+		if (WARN_ONCE(!dqm->sched_running, "Evict when stopped\n"))
+			continue;
+
 		retval = mqd_mgr->destroy_mqd(mqd_mgr, q->mqd,
 				KFD_PREEMPT_TYPE_WAVEFRONT_DRAIN,
 				KFD_UNMAP_LATENCY_MS, q->pipe, q->queue);
@@ -610,7 +631,6 @@ static int evict_process_queues_nocpsch(struct device_queue_manager *dqm,
 			 * maintain a consistent eviction state
 			 */
 			ret = retval;
-		dqm->queue_count--;
 	}
 
 out:
@@ -711,6 +731,11 @@ static int restore_process_queues_nocpsch(struct device_queue_manager *dqm,
 		mqd_mgr = dqm->mqd_mgrs[get_mqd_type_from_queue_type(
 				q->properties.type)];
 		q->properties.is_active = true;
+		dqm->queue_count++;
+
+		if (WARN_ONCE(!dqm->sched_running, "Restore when stopped\n"))
+			continue;
+
 		retval = mqd_mgr->load_mqd(mqd_mgr, q->mqd, q->pipe,
 				       q->queue, &q->properties, mm);
 		if (retval && !ret)
@@ -718,7 +743,6 @@ static int restore_process_queues_nocpsch(struct device_queue_manager *dqm,
 			 * maintain a consistent eviction state
 			 */
 			ret = retval;
-		dqm->queue_count++;
 	}
 	qpd->evicted = 0;
 out:
@@ -915,6 +939,7 @@ static int start_nocpsch(struct device_queue_manager *dqm)
 	
 	if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
 		return pm_init(&dqm->packets, dqm);
+	dqm->sched_running = true;
 
 	return 0;
 }
@@ -923,6 +948,7 @@ static int stop_nocpsch(struct device_queue_manager *dqm)
 {
 	if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
 		pm_uninit(&dqm->packets);
+	dqm->sched_running = false;
 
 	return 0;
 }
@@ -1074,6 +1100,7 @@ static int start_cpsch(struct device_queue_manager *dqm)
 	dqm_lock(dqm);
 	/* clear hang status when driver try to start the hw scheduler */
 	dqm->is_hws_hang = false;
+	dqm->sched_running = true;
 	execute_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_DYNAMIC_QUEUES, 0);
 	dqm_unlock(dqm);
 
@@ -1089,6 +1116,7 @@ static int stop_cpsch(struct device_queue_manager *dqm)
 {
 	dqm_lock(dqm);
 	unmap_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_ALL_QUEUES, 0);
+	dqm->sched_running = false;
 	dqm_unlock(dqm);
 
 	kfd_gtt_sa_free(dqm->dev, dqm->fence_mem);
@@ -1275,9 +1303,10 @@ static int map_queues_cpsch(struct device_queue_manager *dqm)
 {
 	int retval;
 
+	if (!dqm->sched_running)
+		return 0;
 	if (dqm->queue_count <= 0 || dqm->processes_count <= 0)
 		return 0;
-
 	if (dqm->active_runlist)
 		return 0;
 
@@ -1299,6 +1328,8 @@ static int unmap_queues_cpsch(struct device_queue_manager *dqm,
 {
 	int retval = 0;
 
+	if (!dqm->sched_running)
+		return 0;
 	if (dqm->is_hws_hang)
 		return -EIO;
 	if (!dqm->active_runlist)
@@ -1903,6 +1934,12 @@ int dqm_debugfs_hqds(struct seq_file *m, void *data)
 	int pipe, queue;
 	int r = 0;
 
+	if (!dqm->sched_running) {
+		seq_printf(m, " Device is stopped\n");
+
+		return 0;
+	}
+
 	r = dqm->dev->kfd2kgd->hqd_dump(dqm->dev->kgd,
 					KFD_CIK_HIQ_PIPE, KFD_CIK_HIQ_QUEUE,
 					&dump, &n_regs);

drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h

@@ -201,6 +201,7 @@ struct device_queue_manager {
 	bool			is_hws_hang;
 	struct work_struct	hw_exception_work;
 	struct kfd_mem_obj	hiq_sdma_mqd;
+	bool			sched_running;
 };
 
 void device_queue_manager_init_cik(