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

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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->device_stopped 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
device_stopped flag before sending the updated runlist.

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@xxxxxxx>
Signed-off-by: Philip Yang <Philip.Yang@xxxxxxx>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c            |  6 +++---
 drivers/gpu/drm/amd/amdkfd/kfd_device.c             |  5 -----
 .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.c   | 13 ++++++++++---
 .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.h   |  1 +
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index d9e36dbf13d5..40d75c39f08e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -120,13 +120,13 @@ static int kfd_open(struct inode *inode, struct file *filep)
 		return -EPERM;
 	}
 
+	if (kfd_is_locked())
+		return -EAGAIN;
+
 	process = kfd_create_process(filep);
 	if (IS_ERR(process))
 		return PTR_ERR(process);
 
-	if (kfd_is_locked())
-		return -EAGAIN;
-
 	dev_dbg(kfd_device, "process %d opened, compat mode (32 bit) - %d\n",
 		process->pasid, process->is_32bit_user_mode);
 
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 8f4b24e84964..4fa8834ce7cb 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/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;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
index 81fb545cf42c..04a40fabe9d7 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
@@ -915,7 +915,8 @@ 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->device_stopped = false;
+
 	return 0;
 }
 
@@ -923,7 +924,8 @@ static int stop_nocpsch(struct device_queue_manager *dqm)
 {
 	if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
 		pm_uninit(&dqm->packets);
-	
+	dqm->device_stopped = true;
+
 	return 0;
 }
 
@@ -1074,6 +1076,7 @@ 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->device_stopped = false;
 	execute_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_DYNAMIC_QUEUES, 0);
 	dqm_unlock(dqm);
 
@@ -1089,6 +1092,7 @@ static int stop_cpsch(struct device_queue_manager *dqm)
 {
 	dqm_lock(dqm);
 	unmap_queues_cpsch(dqm, KFD_UNMAP_QUEUES_FILTER_ALL_QUEUES, 0);
+	dqm->device_stopped = true;
 	dqm_unlock(dqm);
 
 	kfd_gtt_sa_free(dqm->dev, dqm->fence_mem);
@@ -1275,9 +1279,10 @@ static int map_queues_cpsch(struct device_queue_manager *dqm)
 {
 	int retval;
 
+	if (dqm->device_stopped)
+		return 0;
 	if (dqm->queue_count <= 0 || dqm->processes_count <= 0)
 		return 0;
-
 	if (dqm->active_runlist)
 		return 0;
 
@@ -1299,6 +1304,8 @@ static int unmap_queues_cpsch(struct device_queue_manager *dqm,
 {
 	int retval = 0;
 
+	if (dqm->device_stopped)
+		return 0;
 	if (dqm->is_hws_hang)
 		return -EIO;
 	if (!dqm->active_runlist)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
index 2eaea6b04cbe..44ecdf999ca8 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.h
+++ b/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			device_stopped;
 };
 
 void device_queue_manager_init_cik(
-- 
2.17.1

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