2022-01-23 15:18:10

by Yongzhi Liu

[permalink] [raw]
Subject: [PATCH] drm/v3d: Add missing unlock

[why]
Unlock is needed on the error handling path to prevent dead lock.

[how]
Fix this by adding drm_gem_unlock_reservations on the error handling path.

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/gpu/drm/v3d/v3d_gem.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index c7ed2e1..0c989dc 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -798,6 +798,8 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

if (!render->base.perfmon) {
ret = -ENOENT;
+ drm_gem_unlock_reservations(last_job->bo,
+ last_job->bo_count, &acquire_ctx);
goto fail;
}
}
@@ -1027,6 +1029,8 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
args->perfmon_id);
if (!job->base.perfmon) {
ret = -ENOENT;
+ drm_gem_unlock_reservations(clean_job->bo, clean_job->bo_count,
+ &acquire_ctx);
goto fail;
}
}
--
2.7.4


2022-01-27 00:39:07

by Melissa Wen

[permalink] [raw]
Subject: Re: [PATCH] drm/v3d: Add missing unlock

On 01/22, Yongzhi Liu wrote:
> [why]
> Unlock is needed on the error handling path to prevent dead lock.
>
> [how]
> Fix this by adding drm_gem_unlock_reservations on the error handling path.
>
> Signed-off-by: Yongzhi Liu <[email protected]>
> ---
> drivers/gpu/drm/v3d/v3d_gem.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index c7ed2e1..0c989dc 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -798,6 +798,8 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
>
> if (!render->base.perfmon) {
> ret = -ENOENT;
> + drm_gem_unlock_reservations(last_job->bo,
> + last_job->bo_count, &acquire_ctx);
> goto fail;
Hi,

Nice catch!

As unlock is handle in fail_unreserve, I would suggest you to keep the
failures handling around there. In that case, the goto will target a
place between `fail_unreserve:` and `fail:`, i.e. calls
drm_gem_unlock_reservations (and the following cleanings) but don't call
mutex_unlock.

Thanks,

Melissa

> }
> }
> @@ -1027,6 +1029,8 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
> args->perfmon_id);
> if (!job->base.perfmon) {
> ret = -ENOENT;
> + drm_gem_unlock_reservations(clean_job->bo, clean_job->bo_count,
> + &acquire_ctx);
> goto fail;
> }
> }
> --
> 2.7.4
>

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2022-01-27 17:56:51

by Yongzhi Liu

[permalink] [raw]
Subject: [PATCH v2] drm/v3d: fix missing unlock

[why]
Unlock is needed on the error handling path to prevent dead lock.
v3d_submit_cl_ioctl and v3d_submit_csd_ioctl is missing unlock.

[how]
Fix this by change goto target on the error handling path.
As unlock is handle in fail_unreserve, i keep the failures
handling around there. So the goto targets a place between
`fail_unreserve:` and `fail:`.

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/gpu/drm/v3d/v3d_gem.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index c7ed2e1..d9c7b39 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -798,7 +798,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

if (!render->base.perfmon) {
ret = -ENOENT;
- goto fail;
+ goto v3d_unlock;
}
}

@@ -847,6 +847,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

fail_unreserve:
mutex_unlock(&v3d->sched_lock);
+v3d_unlock:
drm_gem_unlock_reservations(last_job->bo,
last_job->bo_count, &acquire_ctx);
fail:
@@ -1027,7 +1028,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
args->perfmon_id);
if (!job->base.perfmon) {
ret = -ENOENT;
- goto fail;
+ goto v3d_unlock;
}
}

@@ -1056,6 +1057,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,

fail_unreserve:
mutex_unlock(&v3d->sched_lock);
+v3d_unlock:
drm_gem_unlock_reservations(clean_job->bo, clean_job->bo_count,
&acquire_ctx);
fail:
--
2.7.4

2022-01-31 11:00:49

by Melissa Wen

[permalink] [raw]
Subject: Re: [PATCH v2] drm/v3d: fix missing unlock

On 01/27, Yongzhi Liu wrote:
> [why]
> Unlock is needed on the error handling path to prevent dead lock.
> v3d_submit_cl_ioctl and v3d_submit_csd_ioctl is missing unlock.
>
> [how]
> Fix this by change goto target on the error handling path.
s/change/changing/g

I would just say: `Changing the goto to target an error handling path
that includes drm_gem_unlock reservations.`

and drop the explanation below

> As unlock is handle in fail_unreserve, i keep the failures
> handling around there. So the goto targets a place between
> `fail_unreserve:` and `fail:`.
>
> Signed-off-by: Yongzhi Liu <[email protected]>
> ---
> drivers/gpu/drm/v3d/v3d_gem.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> index c7ed2e1..d9c7b39 100644
> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> @@ -798,7 +798,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
>
> if (!render->base.perfmon) {
> ret = -ENOENT;
> - goto fail;
> + goto v3d_unlock;
We usually use a `fail` prefix when handling failures.
A suggestion: `fail_perfmon` ?
> }
> }
>
> @@ -847,6 +847,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,
>
> fail_unreserve:
> mutex_unlock(&v3d->sched_lock);
> +v3d_unlock:
> drm_gem_unlock_reservations(last_job->bo,
> last_job->bo_count, &acquire_ctx);
> fail:
> @@ -1027,7 +1028,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
> args->perfmon_id);
> if (!job->base.perfmon) {
> ret = -ENOENT;
> - goto fail;
> + goto v3d_unlock;
> }
> }
>
> @@ -1056,6 +1057,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
>
> fail_unreserve:
> mutex_unlock(&v3d->sched_lock);
> +v3d_unlock:
> drm_gem_unlock_reservations(clean_job->bo, clean_job->bo_count,
> &acquire_ctx);
> fail:

With these changes, you can include in the next version my r-b:
Reviewed-by: Melissa Wen <[email protected]>

> --
> 2.7.4
>

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2022-01-31 11:04:35

by Yongzhi Liu

[permalink] [raw]
Subject: [PATCH v3] drm/v3d: fix missing unlock

[why]
Unlock is needed on the error handling path to prevent dead lock.
v3d_submit_cl_ioctl and v3d_submit_csd_ioctl is missing unlock.

[how]
Fix this by changing goto target on the error handling path. So
changing the goto to target an error handling path
that includes drm_gem_unlock reservations.

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/gpu/drm/v3d/v3d_gem.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index c7ed2e1..92bc0fa 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -798,7 +798,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

if (!render->base.perfmon) {
ret = -ENOENT;
- goto fail;
+ goto fail_perfmon;
}
}

@@ -847,6 +847,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data,

fail_unreserve:
mutex_unlock(&v3d->sched_lock);
+fail_perfmon:
drm_gem_unlock_reservations(last_job->bo,
last_job->bo_count, &acquire_ctx);
fail:
@@ -1027,7 +1028,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,
args->perfmon_id);
if (!job->base.perfmon) {
ret = -ENOENT;
- goto fail;
+ goto fail_perfmon;
}
}

@@ -1056,6 +1057,7 @@ v3d_submit_csd_ioctl(struct drm_device *dev, void *data,

fail_unreserve:
mutex_unlock(&v3d->sched_lock);
+fail_perfmon:
drm_gem_unlock_reservations(clean_job->bo, clean_job->bo_count,
&acquire_ctx);
fail:
--
2.7.4