| Message ID | 1398157633-31043-1-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 22, 2014 at 11:07:13AM +0200, Daniel Vetter wrote: [...] > diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c > index e768d35ff22e..8db129c44fea 100644 > --- a/drivers/gpu/drm/drm_plane_helper.c > +++ b/drivers/gpu/drm/drm_plane_helper.c > @@ -175,22 +175,7 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, > set.connectors = connector_list; > set.num_connectors = num_connectors; > > - /* > - * set_config() adjusts crtc->primary->fb; however the DRM setplane > - * code that called us expects to handle the framebuffer update and > - * reference counting; save and restore the current fb before > - * calling it. > - * > - * N.B., we call set_config() directly here rather than using > - * drm_mode_set_config_internal. We're reprogramming the same > - * connectors that were already in use, so we shouldn't need the extra > - * cross-CRTC fb refcounting to accomodate stealing connectors. > - * drm_mode_setplane() already handles the basic refcounting for the > - * framebuffers involved in this operation. > - */ > - tmpfb = plane->fb; > ret = crtc->funcs->set_config(&set); > - plane->fb = tmpfb; This makes tmpfb unused. Other than that this looks sane to me and it doesn't make things worse from what I can tell: Tested-by: Thierry Reding <treding@nvidia.com>
On Tue, Apr 22, 2014 at 11:07:13AM +0200, Daniel Vetter wrote: > The introduction of primary planes has apparently caused a bit of fb > refcounting fun for people. That makes it a good time to clean up the > arcane rules and slight differences between ->update_plane and > ->set_config. The new rules are: > > - The core holds a reference for both the new and the old fb (if their > non-NULL of course) while calling into the driver through either > ->update_plane or ->set_config. > > - Drivers may not clobber plane->fb if their callback fails. If they > do that, they need to store a pointer to the old fb in it again. > When calling into the driver plane->fb still points at the current > (old) framebuffer. > > - The core will update the plane->fb pointer on success. Drivers can > do that themselves too. > > - The core will update fb refcounts for the plane->fb pointer, > presuming the drivers hold up their end of the bargain. > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > --- > drivers/gpu/drm/drm_crtc.c | 12 +++++------- > drivers/gpu/drm/drm_plane_helper.c | 15 --------------- > 2 files changed, 5 insertions(+), 22 deletions(-) > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > index d8b7099abece..966b480ed543 100644 > --- a/drivers/gpu/drm/drm_crtc.c > +++ b/drivers/gpu/drm/drm_crtc.c > @@ -2187,24 +2187,24 @@ int drm_mode_setplane(struct drm_device *dev, void *data, > } > > drm_modeset_lock_all(dev); > + old_fb = plane->fb; > ret = plane->funcs->update_plane(plane, crtc, fb, > plane_req->crtc_x, plane_req->crtc_y, > plane_req->crtc_w, plane_req->crtc_h, > plane_req->src_x, plane_req->src_y, > plane_req->src_w, plane_req->src_h); > if (!ret) { > - old_fb = plane->fb; > plane->crtc = crtc; > plane->fb = fb; > - fb = NULL; > } > drm_modeset_unlock_all(dev); > > out: > - if (fb) > - drm_framebuffer_unreference(fb); > + if (plane->fb) > + drm_framebuffer_reference(old_fb); ^^^^^^ That doesn't look right. Also you're now dereferencing plane->fb after you drop the locks. Also i915 fb destruction seems buggy as we do intel_fb->obj->framebuffer_references-- w/o holding struct_mutex. > if (old_fb) > drm_framebuffer_unreference(old_fb); > + drm_framebuffer_unreference(fb); > > return ret; > } > @@ -2239,9 +2239,7 @@ int drm_mode_set_config_internal(struct drm_mode_set *set) > ret = crtc->funcs->set_config(set); > if (ret == 0) { > crtc->primary->crtc = crtc; > - > - /* crtc->fb must be updated by ->set_config, enforces this. */ > - WARN_ON(fb != crtc->primary->fb); > + crtc->primary->fb = fb; > } > > list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { > diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c > index e768d35ff22e..8db129c44fea 100644 > --- a/drivers/gpu/drm/drm_plane_helper.c > +++ b/drivers/gpu/drm/drm_plane_helper.c > @@ -175,22 +175,7 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, > set.connectors = connector_list; > set.num_connectors = num_connectors; > > - /* > - * set_config() adjusts crtc->primary->fb; however the DRM setplane > - * code that called us expects to handle the framebuffer update and > - * reference counting; save and restore the current fb before > - * calling it. > - * > - * N.B., we call set_config() directly here rather than using > - * drm_mode_set_config_internal. We're reprogramming the same > - * connectors that were already in use, so we shouldn't need the extra > - * cross-CRTC fb refcounting to accomodate stealing connectors. > - * drm_mode_setplane() already handles the basic refcounting for the > - * framebuffers involved in this operation. > - */ > - tmpfb = plane->fb; > ret = crtc->funcs->set_config(&set); > - plane->fb = tmpfb; > > kfree(connector_list); > return ret; > -- > 1.9.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel
On Tue, Apr 22, 2014 at 01:06:22PM +0300, Ville Syrjälä wrote: > On Tue, Apr 22, 2014 at 11:07:13AM +0200, Daniel Vetter wrote: > > The introduction of primary planes has apparently caused a bit of fb > > refcounting fun for people. That makes it a good time to clean up the > > arcane rules and slight differences between ->update_plane and > > ->set_config. The new rules are: > > > > - The core holds a reference for both the new and the old fb (if their > > non-NULL of course) while calling into the driver through either > > ->update_plane or ->set_config. > > > > - Drivers may not clobber plane->fb if their callback fails. If they > > do that, they need to store a pointer to the old fb in it again. > > When calling into the driver plane->fb still points at the current > > (old) framebuffer. > > > > - The core will update the plane->fb pointer on success. Drivers can > > do that themselves too. > > > > - The core will update fb refcounts for the plane->fb pointer, > > presuming the drivers hold up their end of the bargain. > > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > --- > > drivers/gpu/drm/drm_crtc.c | 12 +++++------- > > drivers/gpu/drm/drm_plane_helper.c | 15 --------------- > > 2 files changed, 5 insertions(+), 22 deletions(-) > > > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > > index d8b7099abece..966b480ed543 100644 > > --- a/drivers/gpu/drm/drm_crtc.c > > +++ b/drivers/gpu/drm/drm_crtc.c > > @@ -2187,24 +2187,24 @@ int drm_mode_setplane(struct drm_device *dev, void *data, > > } > > > > drm_modeset_lock_all(dev); > > + old_fb = plane->fb; > > ret = plane->funcs->update_plane(plane, crtc, fb, > > plane_req->crtc_x, plane_req->crtc_y, > > plane_req->crtc_w, plane_req->crtc_h, > > plane_req->src_x, plane_req->src_y, > > plane_req->src_w, plane_req->src_h); > > if (!ret) { > > - old_fb = plane->fb; > > plane->crtc = crtc; > > plane->fb = fb; > > - fb = NULL; > > } > > drm_modeset_unlock_all(dev); > > > > out: > > - if (fb) > > - drm_framebuffer_unreference(fb); > > + if (plane->fb) > > + drm_framebuffer_reference(old_fb); > ^^^^^^ > > That doesn't look right. > > Also you're now dereferencing plane->fb after you drop the locks. Oops, will fix. > Also i915 fb destruction seems buggy as we do > intel_fb->obj->framebuffer_references-- w/o holding struct_mutex. Hm, this indeed looks fishy. And the offending patch was actually r-b: you. Not sure what to do here really. -Daniel > > > if (old_fb) > > drm_framebuffer_unreference(old_fb); > > + drm_framebuffer_unreference(fb); > > > > return ret; > > } > > @@ -2239,9 +2239,7 @@ int drm_mode_set_config_internal(struct drm_mode_set *set) > > ret = crtc->funcs->set_config(set); > > if (ret == 0) { > > crtc->primary->crtc = crtc; > > - > > - /* crtc->fb must be updated by ->set_config, enforces this. */ > > - WARN_ON(fb != crtc->primary->fb); > > + crtc->primary->fb = fb; > > } > > > > list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { > > diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c > > index e768d35ff22e..8db129c44fea 100644 > > --- a/drivers/gpu/drm/drm_plane_helper.c > > +++ b/drivers/gpu/drm/drm_plane_helper.c > > @@ -175,22 +175,7 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, > > set.connectors = connector_list; > > set.num_connectors = num_connectors; > > > > - /* > > - * set_config() adjusts crtc->primary->fb; however the DRM setplane > > - * code that called us expects to handle the framebuffer update and > > - * reference counting; save and restore the current fb before > > - * calling it. > > - * > > - * N.B., we call set_config() directly here rather than using > > - * drm_mode_set_config_internal. We're reprogramming the same > > - * connectors that were already in use, so we shouldn't need the extra > > - * cross-CRTC fb refcounting to accomodate stealing connectors. > > - * drm_mode_setplane() already handles the basic refcounting for the > > - * framebuffers involved in this operation. > > - */ > > - tmpfb = plane->fb; > > ret = crtc->funcs->set_config(&set); > > - plane->fb = tmpfb; > > > > kfree(connector_list); > > return ret; > > -- > > 1.9.2 > > > > _______________________________________________ > > dri-devel mailing list > > dri-devel@lists.freedesktop.org > > http://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC
On Tue, Apr 22, 2014 at 04:09:09PM +0200, Daniel Vetter wrote: > On Tue, Apr 22, 2014 at 01:06:22PM +0300, Ville Syrjälä wrote: > > On Tue, Apr 22, 2014 at 11:07:13AM +0200, Daniel Vetter wrote: > > > The introduction of primary planes has apparently caused a bit of fb > > > refcounting fun for people. That makes it a good time to clean up the > > > arcane rules and slight differences between ->update_plane and > > > ->set_config. The new rules are: > > > > > > - The core holds a reference for both the new and the old fb (if their > > > non-NULL of course) while calling into the driver through either > > > ->update_plane or ->set_config. > > > > > > - Drivers may not clobber plane->fb if their callback fails. If they > > > do that, they need to store a pointer to the old fb in it again. > > > When calling into the driver plane->fb still points at the current > > > (old) framebuffer. > > > > > > - The core will update the plane->fb pointer on success. Drivers can > > > do that themselves too. > > > > > > - The core will update fb refcounts for the plane->fb pointer, > > > presuming the drivers hold up their end of the bargain. > > > > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> > > > --- > > > drivers/gpu/drm/drm_crtc.c | 12 +++++------- > > > drivers/gpu/drm/drm_plane_helper.c | 15 --------------- > > > 2 files changed, 5 insertions(+), 22 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c > > > index d8b7099abece..966b480ed543 100644 > > > --- a/drivers/gpu/drm/drm_crtc.c > > > +++ b/drivers/gpu/drm/drm_crtc.c > > > @@ -2187,24 +2187,24 @@ int drm_mode_setplane(struct drm_device *dev, void *data, > > > } > > > > > > drm_modeset_lock_all(dev); > > > + old_fb = plane->fb; > > > ret = plane->funcs->update_plane(plane, crtc, fb, > > > plane_req->crtc_x, plane_req->crtc_y, > > > plane_req->crtc_w, plane_req->crtc_h, > > > plane_req->src_x, plane_req->src_y, > > > plane_req->src_w, plane_req->src_h); > > > if (!ret) { > > > - old_fb = plane->fb; > > > plane->crtc = crtc; > > > plane->fb = fb; > > > - fb = NULL; > > > } > > > drm_modeset_unlock_all(dev); > > > > > > out: > > > - if (fb) > > > - drm_framebuffer_unreference(fb); > > > + if (plane->fb) > > > + drm_framebuffer_reference(old_fb); > > ^^^^^^ > > > > That doesn't look right. > > > > Also you're now dereferencing plane->fb after you drop the locks. > > Oops, will fix. > > > Also i915 fb destruction seems buggy as we do > > intel_fb->obj->framebuffer_references-- w/o holding struct_mutex. > > Hm, this indeed looks fishy. And the offending patch was actually r-b: > you. Dang. I suck. > Not sure what to do here really. Just s/drm_gem_object_unreference_unlocked/drm_gem_object_unreference/ and grab struct_mutex by hand around both operations? > -Daniel > > > > > > if (old_fb) > > > drm_framebuffer_unreference(old_fb); > > > + drm_framebuffer_unreference(fb); > > > > > > return ret; > > > } > > > @@ -2239,9 +2239,7 @@ int drm_mode_set_config_internal(struct drm_mode_set *set) > > > ret = crtc->funcs->set_config(set); > > > if (ret == 0) { > > > crtc->primary->crtc = crtc; > > > - > > > - /* crtc->fb must be updated by ->set_config, enforces this. */ > > > - WARN_ON(fb != crtc->primary->fb); > > > + crtc->primary->fb = fb; > > > } > > > > > > list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { > > > diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c > > > index e768d35ff22e..8db129c44fea 100644 > > > --- a/drivers/gpu/drm/drm_plane_helper.c > > > +++ b/drivers/gpu/drm/drm_plane_helper.c > > > @@ -175,22 +175,7 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, > > > set.connectors = connector_list; > > > set.num_connectors = num_connectors; > > > > > > - /* > > > - * set_config() adjusts crtc->primary->fb; however the DRM setplane > > > - * code that called us expects to handle the framebuffer update and > > > - * reference counting; save and restore the current fb before > > > - * calling it. > > > - * > > > - * N.B., we call set_config() directly here rather than using > > > - * drm_mode_set_config_internal. We're reprogramming the same > > > - * connectors that were already in use, so we shouldn't need the extra > > > - * cross-CRTC fb refcounting to accomodate stealing connectors. > > > - * drm_mode_setplane() already handles the basic refcounting for the > > > - * framebuffers involved in this operation. > > > - */ > > > - tmpfb = plane->fb; > > > ret = crtc->funcs->set_config(&set); > > > - plane->fb = tmpfb; > > > > > > kfree(connector_list); > > > return ret; > > > -- > > > 1.9.2 > > > > > > _______________________________________________ > > > dri-devel mailing list > > > dri-devel@lists.freedesktop.org > > > http://lists.freedesktop.org/mailman/listinfo/dri-devel > > > > -- > > Ville Syrjälä > > Intel OTC > > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch
On Tue, Apr 22, 2014 at 4:28 PM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote: >> Not sure what to do here really. > > Just s/drm_gem_object_unreference_unlocked/drm_gem_object_unreference/ > and grab struct_mutex by hand around both operations? I was kinda hoping for someone to go ahead and fix the entire fb tracking locking madness while at it ;-) I'll do the fixup. -Daniel
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index d8b7099abece..966b480ed543 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -2187,24 +2187,24 @@ int drm_mode_setplane(struct drm_device *dev, void *data, } drm_modeset_lock_all(dev); + old_fb = plane->fb; ret = plane->funcs->update_plane(plane, crtc, fb, plane_req->crtc_x, plane_req->crtc_y, plane_req->crtc_w, plane_req->crtc_h, plane_req->src_x, plane_req->src_y, plane_req->src_w, plane_req->src_h); if (!ret) { - old_fb = plane->fb; plane->crtc = crtc; plane->fb = fb; - fb = NULL; } drm_modeset_unlock_all(dev); out: - if (fb) - drm_framebuffer_unreference(fb); + if (plane->fb) + drm_framebuffer_reference(old_fb); if (old_fb) drm_framebuffer_unreference(old_fb); + drm_framebuffer_unreference(fb); return ret; } @@ -2239,9 +2239,7 @@ int drm_mode_set_config_internal(struct drm_mode_set *set) ret = crtc->funcs->set_config(set); if (ret == 0) { crtc->primary->crtc = crtc; - - /* crtc->fb must be updated by ->set_config, enforces this. */ - WARN_ON(fb != crtc->primary->fb); + crtc->primary->fb = fb; } list_for_each_entry(tmp, &crtc->dev->mode_config.crtc_list, head) { diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c index e768d35ff22e..8db129c44fea 100644 --- a/drivers/gpu/drm/drm_plane_helper.c +++ b/drivers/gpu/drm/drm_plane_helper.c @@ -175,22 +175,7 @@ int drm_primary_helper_update(struct drm_plane *plane, struct drm_crtc *crtc, set.connectors = connector_list; set.num_connectors = num_connectors; - /* - * set_config() adjusts crtc->primary->fb; however the DRM setplane - * code that called us expects to handle the framebuffer update and - * reference counting; save and restore the current fb before - * calling it. - * - * N.B., we call set_config() directly here rather than using - * drm_mode_set_config_internal. We're reprogramming the same - * connectors that were already in use, so we shouldn't need the extra - * cross-CRTC fb refcounting to accomodate stealing connectors. - * drm_mode_setplane() already handles the basic refcounting for the - * framebuffers involved in this operation. - */ - tmpfb = plane->fb; ret = crtc->funcs->set_config(&set); - plane->fb = tmpfb; kfree(connector_list); return ret;
The introduction of primary planes has apparently caused a bit of fb refcounting fun for people. That makes it a good time to clean up the arcane rules and slight differences between ->update_plane and ->set_config. The new rules are: - The core holds a reference for both the new and the old fb (if their non-NULL of course) while calling into the driver through either ->update_plane or ->set_config. - Drivers may not clobber plane->fb if their callback fails. If they do that, they need to store a pointer to the old fb in it again. When calling into the driver plane->fb still points at the current (old) framebuffer. - The core will update the plane->fb pointer on success. Drivers can do that themselves too. - The core will update fb refcounts for the plane->fb pointer, presuming the drivers hold up their end of the bargain. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/drm_crtc.c | 12 +++++------- drivers/gpu/drm/drm_plane_helper.c | 15 --------------- 2 files changed, 5 insertions(+), 22 deletions(-)