drm/amdgpu: change reset lock from mutex to rw_semaphore

clients don't need reset-lock for synchronization when no
GPU recovery.

v2:
change to return the return value of down_read_killable.

v3:
if GPU recovery begin, VF ignore FLR notification.
Reviewed-by: Monk Liu <monk.liu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -951,7 +951,7 @@ struct amdgpu_device {
 
 	atomic_t 			in_gpu_reset;
 	enum pp_mp1_state               mp1_state;
-	struct mutex  lock_reset;
+	struct rw_semaphore reset_sem;
 	struct amdgpu_doorbell_index doorbell_index;
 
 	struct mutex			notifier_lock;

drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c

@@ -101,14 +101,18 @@ static int amdgpu_debugfs_autodump_open(struct inode *inode, struct file *file)
 
 	file->private_data = adev;
 
-	mutex_lock(&adev->lock_reset);
+	ret = down_read_killable(&adev->reset_sem);
+	if (ret)
+		return ret;
+
 	if (adev->autodump.dumping.done) {
 		reinit_completion(&adev->autodump.dumping);
 		ret = 0;
 	} else {
 		ret = -EBUSY;
 	}
-	mutex_unlock(&adev->lock_reset);
+
+	up_read(&adev->reset_sem);
 
 	return ret;
 }
@@ -1242,7 +1246,9 @@ static int amdgpu_debugfs_test_ib(struct seq_file *m, void *data)
 	}
 
 	/* Avoid accidently unparking the sched thread during GPU reset */
-	mutex_lock(&adev->lock_reset);
+	r = down_read_killable(&adev->reset_sem);
+	if (r)
+		return r;
 
 	/* hold on the scheduler */
 	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
@@ -1269,7 +1275,7 @@ static int amdgpu_debugfs_test_ib(struct seq_file *m, void *data)
 		kthread_unpark(ring->sched.thread);
 	}
 
-	mutex_unlock(&adev->lock_reset);
+	up_read(&adev->reset_sem);
 
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
@@ -1459,7 +1465,9 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 		return -ENOMEM;
 
 	/* Avoid accidently unparking the sched thread during GPU reset */
-	mutex_lock(&adev->lock_reset);
+	r = down_read_killable(&adev->reset_sem);
+	if (r)
+		goto pro_end;
 
 	/* stop the scheduler */
 	kthread_park(ring->sched.thread);
@@ -1500,13 +1508,14 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 	/* restart the scheduler */
 	kthread_unpark(ring->sched.thread);
 
-	mutex_unlock(&adev->lock_reset);
+	up_read(&adev->reset_sem);
 
 	ttm_bo_unlock_delayed_workqueue(&adev->mman.bdev, resched);
 
+pro_end:
 	kfree(fences);
 
-	return 0;
+	return r;
 }
 
 static int amdgpu_debugfs_sclk_set(void *data, u64 val)

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c

@@ -3054,7 +3054,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->virt.vf_errors.lock);
 	hash_init(adev->mn_hash);
 	atomic_set(&adev->in_gpu_reset, 0);
-	mutex_init(&adev->lock_reset);
+	init_rwsem(&adev->reset_sem);
 	mutex_init(&adev->psp.mutex);
 	mutex_init(&adev->notifier_lock);
 
@@ -4206,7 +4206,7 @@ static bool amdgpu_device_lock_adev(struct amdgpu_device *adev)
 	if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0)
 		return false;
 
-	mutex_lock(&adev->lock_reset);
+	down_write(&adev->reset_sem);
 
 	atomic_inc(&adev->gpu_reset_counter);
 	switch (amdgpu_asic_reset_method(adev)) {
@@ -4229,7 +4229,7 @@ static void amdgpu_device_unlock_adev(struct amdgpu_device *adev)
 	amdgpu_vf_error_trans_all(adev);
 	adev->mp1_state = PP_MP1_STATE_NONE;
 	atomic_set(&adev->in_gpu_reset, 0);
-	mutex_unlock(&adev->lock_reset);
+	up_write(&adev->reset_sem);
 }
 
 static void amdgpu_device_resume_display_audio(struct amdgpu_device *adev)

drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c

@@ -238,18 +238,14 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 	struct amdgpu_virt *virt = container_of(work, struct amdgpu_virt, flr_work);
 	struct amdgpu_device *adev = container_of(virt, struct amdgpu_device, virt);
 	int timeout = AI_MAILBOX_POLL_FLR_TIMEDOUT;
-	int locked;
 
 	/* block amdgpu_gpu_recover till msg FLR COMPLETE received,
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
-	 *
-	 * we can unlock the lock_reset to allow "amdgpu_job_timedout"
-	 * to run gpu_recover() after FLR_NOTIFICATION_CMPL received
-	 * which means host side had finished this VF's FLR.
 	 */
-	locked = mutex_trylock(&adev->lock_reset);
-	if (locked)
+	if (!down_read_trylock(&adev->reset_sem))
+		return;
+
 	atomic_set(&adev->in_gpu_reset, 1);
 
 	do {
@@ -261,10 +257,8 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 	} while (timeout > 1);
 
 flr_done:
-	if (locked) {
 	atomic_set(&adev->in_gpu_reset, 0);
-		mutex_unlock(&adev->lock_reset);
-	}
+	up_read(&adev->reset_sem);
 
 	/* Trigger recovery for world switch failure if no TDR */
 	if (amdgpu_device_should_recover_gpu(adev)

drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c

@@ -259,18 +259,14 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 	struct amdgpu_virt *virt = container_of(work, struct amdgpu_virt, flr_work);
 	struct amdgpu_device *adev = container_of(virt, struct amdgpu_device, virt);
 	int timeout = NV_MAILBOX_POLL_FLR_TIMEDOUT;
-	int locked;
 
 	/* block amdgpu_gpu_recover till msg FLR COMPLETE received,
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
-	 *
-	 * we can unlock the lock_reset to allow "amdgpu_job_timedout"
-	 * to run gpu_recover() after FLR_NOTIFICATION_CMPL received
-	 * which means host side had finished this VF's FLR.
 	 */
-	locked = mutex_trylock(&adev->lock_reset);
-	if (locked)
+	if (!down_read_trylock(&adev->reset_sem))
+		return;
+
 	atomic_set(&adev->in_gpu_reset, 1);
 
 	do {
@@ -282,10 +278,8 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 	} while (timeout > 1);
 
 flr_done:
-	if (locked) {
 	atomic_set(&adev->in_gpu_reset, 0);
-		mutex_unlock(&adev->lock_reset);
-	}
+	up_read(&adev->reset_sem);
 
 	/* Trigger recovery for world switch failure if no TDR */
 	if (amdgpu_device_should_recover_gpu(adev)