drm/crc-debugfs: User irqsafe spinlock in drm_crtc_add_crc_entry
diff mbox series

Message ID 20190605194556.16744-1-daniel.vetter@ffwll.ch
State New
Headers show
Series
  • drm/crc-debugfs: User irqsafe spinlock in drm_crtc_add_crc_entry
Related show

Commit Message

Daniel Vetter June 5, 2019, 7:45 p.m. UTC
We can be called from any context, we need to be prepared.

Noticed this while hacking on vkms, which calls this function from a
normal worker. Which really upsets lockdep.

Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/drm_debugfs_crc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Ville Syrjälä June 6, 2019, 8:12 a.m. UTC | #1
On Wed, Jun 05, 2019 at 09:45:56PM +0200, Daniel Vetter wrote:
> We can be called from any context, we need to be prepared.
> 
> Noticed this while hacking on vkms, which calls this function from a
> normal worker. Which really upsets lockdep.
> 
> Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> Cc: Emil Velikov <emil.velikov@collabora.com>
> Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/drm_debugfs_crc.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> index 585169f0dcc5..7f35b5ba1924 100644
> --- a/drivers/gpu/drm/drm_debugfs_crc.c
> +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> @@ -396,8 +396,9 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
>  	struct drm_crtc_crc *crc = &crtc->crc;
>  	struct drm_crtc_crc_entry *entry;
>  	int head, tail;
> +	unsigned long flags;
>  
> -	spin_lock(&crc->lock);
> +	spin_lock_irqsave(&crc->lock, flags);
>  
>  	/* Caller may not have noticed yet that userspace has stopped reading */
>  	if (!crc->entries) {
> @@ -428,7 +429,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
>  	head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
>  	crc->head = head;
>  
> -	spin_unlock(&crc->lock);
> +	spin_unlock_irqrestore(&crc->lock, flags);
>  
>  	wake_up_interruptible(&crc->wq);
>  
> -- 
> 2.20.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
Benjamin Gaignard June 6, 2019, 8:27 a.m. UTC | #2
Le jeu. 6 juin 2019 à 10:12, Ville Syrjälä
<ville.syrjala@linux.intel.com> a écrit :
>
> On Wed, Jun 05, 2019 at 09:45:56PM +0200, Daniel Vetter wrote:
> > We can be called from any context, we need to be prepared.
> >
> > Noticed this while hacking on vkms, which calls this function from a
> > normal worker. Which really upsets lockdep.
> >
> > Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> > Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> > Cc: Emil Velikov <emil.velikov@collabora.com>
> > Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

>
> > ---
> >  drivers/gpu/drm/drm_debugfs_crc.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> > index 585169f0dcc5..7f35b5ba1924 100644
> > --- a/drivers/gpu/drm/drm_debugfs_crc.c
> > +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> > @@ -396,8 +396,9 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
> >       struct drm_crtc_crc *crc = &crtc->crc;
> >       struct drm_crtc_crc_entry *entry;
> >       int head, tail;
> > +     unsigned long flags;
> >
> > -     spin_lock(&crc->lock);
> > +     spin_lock_irqsave(&crc->lock, flags);
> >
> >       /* Caller may not have noticed yet that userspace has stopped reading */
> >       if (!crc->entries) {
> > @@ -428,7 +429,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
> >       head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
> >       crc->head = head;
> >
> > -     spin_unlock(&crc->lock);
> > +     spin_unlock_irqrestore(&crc->lock, flags);
> >
> >       wake_up_interruptible(&crc->wq);
> >
> > --
> > 2.20.1
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
> --
> Ville Syrjälä
> Intel
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
Daniel Vetter June 6, 2019, 9:35 a.m. UTC | #3
On Thu, Jun 06, 2019 at 10:27:23AM +0200, Benjamin Gaignard wrote:
> Le jeu. 6 juin 2019 à 10:12, Ville Syrjälä
> <ville.syrjala@linux.intel.com> a écrit :
> >
> > On Wed, Jun 05, 2019 at 09:45:56PM +0200, Daniel Vetter wrote:
> > > We can be called from any context, we need to be prepared.
> > >
> > > Noticed this while hacking on vkms, which calls this function from a
> > > normal worker. Which really upsets lockdep.
> > >
> > > Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> > > Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
> > > Cc: Emil Velikov <emil.velikov@collabora.com>
> > > Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> >
> > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

Thanks for taking a look, patch pushed to drm-misc-next.
-Daniel

> 
> >
> > > ---
> > >  drivers/gpu/drm/drm_debugfs_crc.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
> > > index 585169f0dcc5..7f35b5ba1924 100644
> > > --- a/drivers/gpu/drm/drm_debugfs_crc.c
> > > +++ b/drivers/gpu/drm/drm_debugfs_crc.c
> > > @@ -396,8 +396,9 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
> > >       struct drm_crtc_crc *crc = &crtc->crc;
> > >       struct drm_crtc_crc_entry *entry;
> > >       int head, tail;
> > > +     unsigned long flags;
> > >
> > > -     spin_lock(&crc->lock);
> > > +     spin_lock_irqsave(&crc->lock, flags);
> > >
> > >       /* Caller may not have noticed yet that userspace has stopped reading */
> > >       if (!crc->entries) {
> > > @@ -428,7 +429,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
> > >       head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
> > >       crc->head = head;
> > >
> > > -     spin_unlock(&crc->lock);
> > > +     spin_unlock_irqrestore(&crc->lock, flags);
> > >
> > >       wake_up_interruptible(&crc->wq);
> > >
> > > --
> > > 2.20.1
> > >
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> >
> > --
> > Ville Syrjälä
> > Intel
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel

Patch
diff mbox series

diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
index 585169f0dcc5..7f35b5ba1924 100644
--- a/drivers/gpu/drm/drm_debugfs_crc.c
+++ b/drivers/gpu/drm/drm_debugfs_crc.c
@@ -396,8 +396,9 @@  int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 	struct drm_crtc_crc *crc = &crtc->crc;
 	struct drm_crtc_crc_entry *entry;
 	int head, tail;
+	unsigned long flags;
 
-	spin_lock(&crc->lock);
+	spin_lock_irqsave(&crc->lock, flags);
 
 	/* Caller may not have noticed yet that userspace has stopped reading */
 	if (!crc->entries) {
@@ -428,7 +429,7 @@  int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 	head = (head + 1) & (DRM_CRC_ENTRIES_NR - 1);
 	crc->head = head;
 
-	spin_unlock(&crc->lock);
+	spin_unlock_irqrestore(&crc->lock, flags);
 
 	wake_up_interruptible(&crc->wq);