Re: [PATCH V1 1/2] drm/amdgpu/userq: avoid uneccessary locking in amdgpu_userq_create
On 4/8/26 10:36, Khatri, Sunil wrote:
>
> On 08-04-2026 01:53 pm, Christian König wrote:
>> On 4/8/26 07:36, Sunil Khatri wrote:
>>> Reorganise code to avoid holding mutex userq_mutex while
>>> also trying to grab exec lock ww_mutex where its not needed
>>> for function amdgpu_userq_input_va_validate
>>>
>>> Signed-off-by: Sunil Khatri
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 33 +++
>>> 1 file changed, 15 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> index 3a6e7a569c78..3f502c18879a 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
>>> @@ -737,28 +737,17 @@ amdgpu_userq_create(struct drm_file *filp, union
>>> drm_amdgpu_userq *args)
>>> return r;
>>> }
>>>
>>> - /*
>>> -* There could be a situation that we are creating a new queue while
>>> -* the other queues under this UQ_mgr are suspended. So if there is any
>>> -* resume work pending, wait for it to get done.
>>> -*
>>> -* This will also make sure we have a valid eviction fence ready to be
>>> used.
>>> -*/
>>> - amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
>>> -
>>> uq_funcs = adev->userq_funcs[args->in.ip_type];
>>> if (!uq_funcs) {
>>> drm_file_err(uq_mgr->file, "Usermode queue is not supported for
>>> this IP (%u)\n",
>>> args->in.ip_type);
>>> - r = -EINVAL;
>>> - goto unlock;
>>> + return -EINVAL;
>>> }
>>>
>>> queue = kzalloc(sizeof(struct amdgpu_usermode_queue), GFP_KERNEL);
>>> if (!queue) {
>>> drm_file_err(uq_mgr->file, "Failed to allocate memory for
>>> queue\n");
>>> - r = -ENOMEM;
>>> - goto unlock;
>>> + return -ENOMEM;
>>> }
>>>
>>> INIT_LIST_HEAD(&queue->userq_va_list);
>>> @@ -781,12 +770,21 @@ amdgpu_userq_create(struct drm_file *filp, union
>>> drm_amdgpu_userq *args)
>>> goto free_queue;
>>> }
>>>
>>> + /*
>>> +* There could be a situation that we are creating a new queue while
>>> +* the other queues under this UQ_mgr are suspended. So if there is any
>>> +* resume work pending, wait for it to get done.
>>> +*
>>> +* This will also make sure we have a valid eviction fence ready to be
>>> used.
>>> +*/
>>> + amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
>> Even that position is not correct. After grabbing the userq_mutex we can't
>> allocate memory any more.
>>
>>> +
>>> /* Convert relative doorbell offset into absolute doorbell index */
>>> index = amdgpu_userq_get_doorbell_index(uq_mgr, &db_info, filp);
>>> if (index == (uint64_t)-EINVAL) {
>>> drm_file_err(uq_mgr->file, "Failed to get doorbell for
>>> queue\n");
>>> r = -EINVAL;
>>> - goto free_queue;
>>> + goto unlock;
>>> }
>>>
>>> queue->doorbell_index = index;
>>> @@ -794,7 +792,7 @@ amdgpu_userq_create(struct drm_file *filp, union
>>> drm_amdgpu_userq *args)
>>> r = amdgpu_userq_fence_driver_alloc(adev, &queue->fence_drv);
>> So doing that here is also forbidden.
> If i am not wrong we could move this whole code including
> amdgpu_userq_fence_driver_alloc and above out of mutex. Does that sounds
> correct ?
At least of hand, yes. We only need to hold the mutex when finally talking to
the HW to enable the new queue.
Regards,
Christian.
Regards Sunil khatri
>> Regards,
>> Christian.
>>
>>> if (r) {
>>> drm_file_err(uq_mgr->file, "Failed to alloc fence driver\n");
>>> - goto free_queue;
>>> + goto unlock;
>>> }
>>>
>>> r = uq_funcs->mqd_create(queue, &args->in);
>>> @@ -858,11 +856,10 @@ amdgpu_userq_create(struct drm_file *filp, union
>>> drm_amdgpu_userq *args)
>>> up_read(&adev->reset_domain->sem);
>>> clean_fence_driver:
>>> amdgpu_userq_fence_driver_free(queue);
>>> -free_queue:
>>> - kfree(queue);
>>> unlock:
>>> mutex_unlock(&uq_mgr->userq_mutex);
>>> -
>>> +free_queue:
>>> + kfree(queue);
>>> return r;
>>> }
>>>
Re: [PATCH V1 1/2] drm/amdgpu/userq: avoid uneccessary locking in amdgpu_userq_create
On 08-04-2026 01:53 pm, Christian König wrote:
On 4/8/26 07:36, Sunil Khatri wrote:
Reorganise code to avoid holding mutex userq_mutex while
also trying to grab exec lock ww_mutex where its not needed
for function amdgpu_userq_input_va_validate
Signed-off-by: Sunil Khatri
---
drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 33 +++
1 file changed, 15 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index 3a6e7a569c78..3f502c18879a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -737,28 +737,17 @@ amdgpu_userq_create(struct drm_file *filp, union
drm_amdgpu_userq *args)
return r;
}
- /*
-* There could be a situation that we are creating a new queue while
-* the other queues under this UQ_mgr are suspended. So if there is any
-* resume work pending, wait for it to get done.
-*
-* This will also make sure we have a valid eviction fence ready to be
used.
-*/
- amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
-
uq_funcs = adev->userq_funcs[args->in.ip_type];
if (!uq_funcs) {
drm_file_err(uq_mgr->file, "Usermode queue is not supported for this
IP (%u)\n",
args->in.ip_type);
- r = -EINVAL;
- goto unlock;
+ return -EINVAL;
}
queue = kzalloc(sizeof(struct amdgpu_usermode_queue), GFP_KERNEL);
if (!queue) {
drm_file_err(uq_mgr->file, "Failed to allocate memory for
queue\n");
- r = -ENOMEM;
- goto unlock;
+ return -ENOMEM;
}
INIT_LIST_HEAD(&queue->userq_va_list);
@@ -781,12 +770,21 @@ amdgpu_userq_create(struct drm_file *filp, union
drm_amdgpu_userq *args)
goto free_queue;
}
+ /*
+* There could be a situation that we are creating a new queue while
+* the other queues under this UQ_mgr are suspended. So if there is any
+* resume work pending, wait for it to get done.
+*
+* This will also make sure we have a valid eviction fence ready to be
used.
+*/
+ amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
Even that position is not correct. After grabbing the userq_mutex we can't
allocate memory any more.
+
/* Convert relative doorbell offset into absolute doorbell index */
index = amdgpu_userq_get_doorbell_index(uq_mgr, &db_info, filp);
if (index == (uint64_t)-EINVAL) {
drm_file_err(uq_mgr->file, "Failed to get doorbell for
queue\n");
r = -EINVAL;
- goto free_queue;
+ goto unlock;
}
queue->doorbell_index = index;
@@ -794,7 +792,7 @@ amdgpu_userq_create(struct drm_file *filp, union
drm_amdgpu_userq *args)
r = amdgpu_userq_fence_driver_alloc(adev, &queue->fence_drv);
So doing that here is also forbidden.
If i am not wrong we could move this whole code including
amdgpu_userq_fence_driver_alloc and above out of mutex. Does that sounds
correct ? Regards Sunil khatri
Regards,
Christian.
if (r) {
drm_file_err(uq_mgr->file, "Failed to alloc fence driver\n");
- goto free_queue;
+ goto unlock;
}
r = uq_funcs->mqd_create(queue, &args->in);
@@ -858,11 +856,10 @@ amdgpu_userq_create(struct drm_file *filp, union
drm_amdgpu_userq *args)
up_read(&adev->reset_domain->sem);
clean_fence_driver:
amdgpu_userq_fence_driver_free(queue);
-free_queue:
- kfree(queue);
unlock:
mutex_unlock(&uq_mgr->userq_mutex);
-
+free_queue:
+ kfree(queue);
return r;
}
Re: [PATCH V1 1/2] drm/amdgpu/userq: avoid uneccessary locking in amdgpu_userq_create
On 4/8/26 07:36, Sunil Khatri wrote:
> Reorganise code to avoid holding mutex userq_mutex while
> also trying to grab exec lock ww_mutex where its not needed
> for function amdgpu_userq_input_va_validate
>
> Signed-off-by: Sunil Khatri
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 33 +++
> 1 file changed, 15 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> index 3a6e7a569c78..3f502c18879a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> @@ -737,28 +737,17 @@ amdgpu_userq_create(struct drm_file *filp, union
> drm_amdgpu_userq *args)
> return r;
> }
>
> - /*
> - * There could be a situation that we are creating a new queue while
> - * the other queues under this UQ_mgr are suspended. So if there is any
> - * resume work pending, wait for it to get done.
> - *
> - * This will also make sure we have a valid eviction fence ready to be
> used.
> - */
> - amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
> -
> uq_funcs = adev->userq_funcs[args->in.ip_type];
> if (!uq_funcs) {
> drm_file_err(uq_mgr->file, "Usermode queue is not supported for
> this IP (%u)\n",
>args->in.ip_type);
> - r = -EINVAL;
> - goto unlock;
> + return -EINVAL;
> }
>
> queue = kzalloc(sizeof(struct amdgpu_usermode_queue), GFP_KERNEL);
> if (!queue) {
> drm_file_err(uq_mgr->file, "Failed to allocate memory for
> queue\n");
> - r = -ENOMEM;
> - goto unlock;
> + return -ENOMEM;
> }
>
> INIT_LIST_HEAD(&queue->userq_va_list);
> @@ -781,12 +770,21 @@ amdgpu_userq_create(struct drm_file *filp, union
> drm_amdgpu_userq *args)
> goto free_queue;
> }
>
> + /*
> + * There could be a situation that we are creating a new queue while
> + * the other queues under this UQ_mgr are suspended. So if there is any
> + * resume work pending, wait for it to get done.
> + *
> + * This will also make sure we have a valid eviction fence ready to be
> used.
> + */
> + amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
Even that position is not correct. After grabbing the userq_mutex we can't
allocate memory any more.
> +
> /* Convert relative doorbell offset into absolute doorbell index */
> index = amdgpu_userq_get_doorbell_index(uq_mgr, &db_info, filp);
> if (index == (uint64_t)-EINVAL) {
> drm_file_err(uq_mgr->file, "Failed to get doorbell for
> queue\n");
> r = -EINVAL;
> - goto free_queue;
> + goto unlock;
> }
>
> queue->doorbell_index = index;
> @@ -794,7 +792,7 @@ amdgpu_userq_create(struct drm_file *filp, union
> drm_amdgpu_userq *args)
> r = amdgpu_userq_fence_driver_alloc(adev, &queue->fence_drv);
So doing that here is also forbidden.
Regards,
Christian.
> if (r) {
> drm_file_err(uq_mgr->file, "Failed to alloc fence driver\n");
> - goto free_queue;
> + goto unlock;
> }
>
> r = uq_funcs->mqd_create(queue, &args->in);
> @@ -858,11 +856,10 @@ amdgpu_userq_create(struct drm_file *filp, union
> drm_amdgpu_userq *args)
> up_read(&adev->reset_domain->sem);
> clean_fence_driver:
> amdgpu_userq_fence_driver_free(queue);
> -free_queue:
> - kfree(queue);
> unlock:
> mutex_unlock(&uq_mgr->userq_mutex);
> -
> +free_queue:
> + kfree(queue);
> return r;
> }
>
