| Message ID | 1401959523-25197-1-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 5, 2014 at 5:12 AM, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > I've fumbled my own idea and enthusiastically wrapped all the > getconnector code with the connection_mutex. But we only need it to > chase the connector->encoder link. Even there it's not really needed > since races with userspace won't matter, but better paranoid and > consistent about this stuff. > > If we grap it everywhere connector probe callbacks can't grab it > themselves, which means they'll deadlock. i915 does that for the load > detect pipe. Furthermore i915 needs to do a ww dance since we also > need to grab the mutex of the load detect crtc. > > This is a regression from > > commit 6e9f798d91c526982cca0026cd451e8fdbf18aaf > Author: Daniel Vetter <daniel.vetter@ffwll.ch> > Date: Thu May 29 23:54:47 2014 +0200 > > drm: Split connection_mutex out of mode_config.mutex (v3) > > Cc: Rob Clark <robdclark@gmail.com> > Cc: Dave Airlie <airlied@redhat.com> > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> > Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Rob Clark <robdclark@gmail.com> > --- > drivers/gpu/drm/drm_crtc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > index b8cc4fe0a0f7..fe94cc10cd35 100644 > --- a/drivers/gpu/drm/drm_crtc.c > +++ b/drivers/gpu/drm/drm_crtc.c > @@ -1838,7 +1838,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, > DRM_DEBUG_KMS("[CONNECTOR:%d:?]\n", out_resp->connector_id); > > mutex_lock(&dev->mode_config.mutex); > - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); > > connector = drm_connector_find(dev, out_resp->connector_id); > if (!connector) { > @@ -1872,10 +1871,12 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, > out_resp->mm_height = connector->display_info.height_mm; > out_resp->subpixel = connector->display_info.subpixel_order; > out_resp->connection = connector->status; > + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); > if (connector->encoder) > out_resp->encoder_id = connector->encoder->base.id; > else > out_resp->encoder_id = 0; > + drm_modeset_unlock(&dev->mode_config.connection_mutex); > > /* > * This ioctl is called twice, once to determine how much space is > @@ -1937,7 +1938,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, > out_resp->count_encoders = encoders_count; > > out: > - drm_modeset_unlock(&dev->mode_config.connection_mutex); > mutex_unlock(&dev->mode_config.mutex); > > return ret; > -- > 2.0.0 >
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index b8cc4fe0a0f7..fe94cc10cd35 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1838,7 +1838,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, DRM_DEBUG_KMS("[CONNECTOR:%d:?]\n", out_resp->connector_id); mutex_lock(&dev->mode_config.mutex); - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); connector = drm_connector_find(dev, out_resp->connector_id); if (!connector) { @@ -1872,10 +1871,12 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, out_resp->mm_height = connector->display_info.height_mm; out_resp->subpixel = connector->display_info.subpixel_order; out_resp->connection = connector->status; + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); if (connector->encoder) out_resp->encoder_id = connector->encoder->base.id; else out_resp->encoder_id = 0; + drm_modeset_unlock(&dev->mode_config.connection_mutex); /* * This ioctl is called twice, once to determine how much space is @@ -1937,7 +1938,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, out_resp->count_encoders = encoders_count; out: - drm_modeset_unlock(&dev->mode_config.connection_mutex); mutex_unlock(&dev->mode_config.mutex); return ret;
I've fumbled my own idea and enthusiastically wrapped all the getconnector code with the connection_mutex. But we only need it to chase the connector->encoder link. Even there it's not really needed since races with userspace won't matter, but better paranoid and consistent about this stuff. If we grap it everywhere connector probe callbacks can't grab it themselves, which means they'll deadlock. i915 does that for the load detect pipe. Furthermore i915 needs to do a ww dance since we also need to grab the mutex of the load detect crtc. This is a regression from commit 6e9f798d91c526982cca0026cd451e8fdbf18aaf Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Thu May 29 23:54:47 2014 +0200 drm: Split connection_mutex out of mode_config.mutex (v3) Cc: Rob Clark <robdclark@gmail.com> Cc: Dave Airlie <airlied@redhat.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/drm_crtc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)