Re: [PATCH v3] drm/amdgpu: change reset lock from mutex to rw_semaphore

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 21.08.20 um 05:47 schrieb Dennis Li:
> 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.
>
> Signed-off-by: Dennis Li <Dennis.Li@xxxxxxx>

Acked-by: Christian König <christian.koenig@xxxxxxx>

> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index c8aec832b244..ec11ed2a9ca4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -954,7 +954,7 @@ 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;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> index 79b397800cbc..cc5c7f81c540 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> +++ b/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)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 78fd2c9a7b7d..82242e2f5658 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/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)
> diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> index f27d83f2de78..9c07014d9bd6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> @@ -238,19 +238,15 @@ 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)
> -		atomic_set(&adev->in_gpu_reset, 1);
> +	if (!down_read_trylock(&adev->reset_sem))
> +		return;
> +
> +	atomic_set(&adev->in_gpu_reset, 1);
>   
>   	do {
>   		if (xgpu_ai_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL)
> @@ -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);
> -	}
> +	atomic_set(&adev->in_gpu_reset, 0);
> +	up_read(&adev->reset_sem);
>   
>   	/* Trigger recovery for world switch failure if no TDR */
>   	if (amdgpu_device_should_recover_gpu(adev)
> diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> index 3cb10ab943a6..9c23abf9b140 100644
> --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> @@ -259,19 +259,15 @@ 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)
> -		atomic_set(&adev->in_gpu_reset, 1);
> +	if (!down_read_trylock(&adev->reset_sem))
> +		return;
> +
> +	atomic_set(&adev->in_gpu_reset, 1);
>   
>   	do {
>   		if (xgpu_nv_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL)
> @@ -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);
> -	}
> +	atomic_set(&adev->in_gpu_reset, 0);
> +	up_read(&adev->reset_sem);
>   
>   	/* Trigger recovery for world switch failure if no TDR */
>   	if (amdgpu_device_should_recover_gpu(adev)

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