[PATCH v3] drm: drm_vblank_cleanup: WARN when refcount > 0

[PATCH v3] drm: drm_vblank_cleanup: WARN when refcount > 0

[PrasannaKumar Muralidharan]

Warn when refcount > 0 in drm_vblank_cleanup.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
 drivers/gpu/drm/drm_vblank.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 70f2b95..3e61aeb 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -405,6 +405,8 @@ void drm_vblank_cleanup(struct drm_device *dev)
 	for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
 		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
 
+		WARN_ON(atomic_read(&vblank->refcount) > 0);
+
 		WARN_ON(READ_ONCE(vblank->enabled) &&
 			drm_core_check_feature(dev, DRIVER_MODESET));
 
-- 
2.10.0

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Re: [PATCH v3] drm: drm_vblank_cleanup: WARN when refcount > 0

[PrasannaKumar Muralidharan]

Hi,

On 13 October 2017 at 08:58, PrasannaKumar Muralidharan
<prasannatsmkumar@gmail.com> wrote:
> Warn when refcount > 0 in drm_vblank_cleanup.
>
> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
> ---
>  drivers/gpu/drm/drm_vblank.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> index 70f2b95..3e61aeb 100644
> --- a/drivers/gpu/drm/drm_vblank.c
> +++ b/drivers/gpu/drm/drm_vblank.c
> @@ -405,6 +405,8 @@ void drm_vblank_cleanup(struct drm_device *dev)
>         for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
>                 struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
>
> +               WARN_ON(atomic_read(&vblank->refcount) > 0);
> +
>                 WARN_ON(READ_ONCE(vblank->enabled) &&
>                         drm_core_check_feature(dev, DRIVER_MODESET));
>
> --
> 2.10.0
>

Looking at the CI logs, realised that the patch I used for testing had
a problem. I used drm_crtc_vblank_put instead of drm_crtc_vblank_get.
I do see that the warning is generated but I am wondering whether it
is correct.

If it is not correct I will resend corrected test patch. Please let me know.

Thanks,
PrasannaKumar
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[PATCH v3] drm: drm_vblank_cleanup: WARN when refcount > 0

[PrasannaKumar Muralidharan]

Warn when refcount > 0 in drm_vblank_cleanup.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
Changes in v3:
* Dropped i915 patch that is used for testing this.

No changes in v2.

 drivers/gpu/drm/drm_vblank.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 70f2b95..3e61aeb 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -405,6 +405,8 @@ void drm_vblank_cleanup(struct drm_device *dev)
 	for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
 		struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
 
+		WARN_ON(atomic_read(&vblank->refcount) > 0);
+
 		WARN_ON(READ_ONCE(vblank->enabled) &&
 			drm_core_check_feature(dev, DRIVER_MODESET));
 
-- 
2.10.0

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Re: [PATCH v3] drm: drm_vblank_cleanup: WARN when refcount > 0

[PrasannaKumar Muralidharan]

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Hi Chris,

Sorry I missed adding you in to list while sending the vblank refcount
patch. Hope you saw that.

On 25-Oct-2017 9:55 PM, "PrasannaKumar Muralidharan" <
prasannatsmkumar@gmail.com> wrote:

Warn when refcount > 0 in drm_vblank_cleanup.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
Changes in v3:
* Dropped i915 patch that is used for testing this.

No changes in v2.

 drivers/gpu/drm/drm_vblank.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index 70f2b95..3e61aeb 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -405,6 +405,8 @@ void drm_vblank_cleanup(struct drm_device *dev)
        for (pipe = 0; pipe < dev->num_crtcs; pipe++) {
                struct drm_vblank_crtc *vblank = &dev->vblank[pipe];

+               WARN_ON(atomic_read(&vblank->refcount) > 0);
+
                WARN_ON(READ_ONCE(vblank->enabled) &&
                        drm_core_check_feature(dev, DRIVER_MODESET));

--
2.10.0


As you anticipated Intel CI found that this patch triggers the non zero
vblank refcount warning on module unload.

Please advice on what to do next. Should I don't think I have to do
something for this patch. If that's not the case please let me know what to
do from my side for this patch.

Note: Replying from an Android device. Please forgive typos.

Thanks and regards,
PrasannaKumar

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