[AMD Official Use Only - Internal Distribution Only]
Hi, Christian,
Thanks for your review. I will update it according to your suggestion.
Best Regards
Dennis Li
-----Original Message-----
From: Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: Thursday, August 20, 2020 5:11 PM
To: Li, Dennis <Dennis.Li@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>; Kuehling, Felix <Felix.Kuehling@xxxxxxx>; Zhang, Hawking <Hawking.Zhang@xxxxxxx>; Koenig, Christian <Christian.Koenig@xxxxxxx>
Subject: Re: [PATCH] drm/amdgpu: change reset lock from mutex to rw_semaphore
Am 20.08.20 um 04:09 schrieb Dennis Li:
> clients don't need reset-lock for synchronization when no GPU
> recovery.
>
> Signed-off-by: Dennis Li <Dennis.Li@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..0090e850eab9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
> @@ -101,14 +101,17 @@ static int amdgpu_debugfs_autodump_open(struct
> inode *inode, struct file *file)
>
> file->private_data = adev;
>
> - mutex_lock(&adev->lock_reset);
> + if (down_read_killable(&adev->reset_sem))
> + return -EINTR;
Better use ret = down_read_killable(); if (ret) return ret; here. Same for all other places of course.
> +
> 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 +1245,8 @@ 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);
> + if (down_read_killable(&adev->reset_sem))
> + return -EINTR;
>
> /* hold on the scheduler */
> for (i = 0; i < AMDGPU_MAX_RINGS; i++) { @@ -1269,7 +1273,7 @@
> 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 +1463,10 @@ 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);
> + if (down_read_killable(&adev->reset_sem)) {
> + kfree(fences);
> + return -EINTR;
Maybe better use a "goto err;" style error handling here.
> + }
>
> /* stop the scheduler */
> kthread_park(ring->sched.thread);
> @@ -1500,7 +1507,7 @@ 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);
>
> 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..8ac63f13fc6f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> @@ -238,19 +238,12 @@ 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);
> + down_read(&adev->reset_sem);
Somebody from the virtualization team should take a look at this as well.
Christian.
>
> do {
> if (xgpu_ai_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL)
> @@ -261,10 +254,7 @@ 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)
> diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> index 3cb10ab943a6..bcc583f087e7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
> @@ -259,19 +259,12 @@ 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);
> + down_read(&adev->reset_sem);
>
> do {
> if (xgpu_nv_mailbox_peek_msg(adev) == IDH_FLR_NOTIFICATION_CMPL)
> @@ -282,10 +275,7 @@ 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)
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