Re: [PATCH] drm/crc-debugfs: User irqsafe spinlock in drm_crtc_add_crc_entry

[Daniel Vetter <daniel@ffwll.ch>]

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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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