| Message ID | 20160607152625.9511-6-thierry.reding@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jun 07, 2016 at 05:26:21PM +0200, Thierry Reding wrote: > From: Thierry Reding <treding@nvidia.com> > > Introduce a new top-level lock for the FB helper code. This will allow > better locking granularity and avoid the need to abuse modeset locking > for this purpose instead. > > Signed-off-by: Thierry Reding <treding@nvidia.com> I think this is now too much locking, and ime too much locking only leads to massive confusion. It'd be great if we can clean this up (maybe in a follow-up patch, maybe in this one here) and restrict the core locks to just where we need them: So all the places that look at probe state need dev->mode_config.mutex, all the places that change modeset state need the modeset locks. But e.g. add/remove_one_connector only need the new fb_helper->lock I think. In the future we might grabbing the other locks even down into the legacy/atomic fbdev implementations. > --- > drivers/gpu/drm/drm_fb_helper.c | 27 ++++++++++++++++++++++++++- > include/drm/drm_fb_helper.h | 5 +++++ > 2 files changed, 31 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c > index 252c7557bdb5..f7722bcb0064 100644 > --- a/drivers/gpu/drm/drm_fb_helper.c > +++ b/drivers/gpu/drm/drm_fb_helper.c > @@ -105,6 +105,7 @@ static int __drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, > if (!drm_fbdev_emulation) > return 0; > > + WARN_ON(!mutex_is_locked(&fb_helper->lock)); > WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex)); > > count = fb_helper->connector_count + 1; > @@ -127,6 +128,7 @@ static int __drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, > drm_connector_reference(connector); > conn->connector = connector; > fb_helper->connector_info[fb_helper->connector_count++] = conn; > + > return 0; > } > > @@ -135,11 +137,13 @@ int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, > { > int err; > > + mutex_lock(&fb_helper->lock); > mutex_lock(&fb_helper->dev->mode_config.mutex); > > err = __drm_fb_helper_add_one_connector(fb_helper, connector); > > mutex_unlock(&fb_helper->dev->mode_config.mutex); > + mutex_unlock(&fb_helper->lock); > > return err; > } > @@ -168,6 +172,7 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) > if (!drm_fbdev_emulation) > return 0; > > + mutex_lock(&fb_helper->lock); > mutex_lock(&dev->mode_config.mutex); > > drm_for_each_connector(connector, dev) { > @@ -184,6 +189,7 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) > } > > mutex_unlock(&dev->mode_config.mutex); > + mutex_unlock(&fb_helper->lock); > > return ret; > } > @@ -198,6 +204,7 @@ static int __drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper, > if (!drm_fbdev_emulation) > return 0; > > + WARN_ON(!mutex_is_locked(&fb_helper->lock)); > WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex)); > > for (i = 0; i < fb_helper->connector_count; i++) { > @@ -225,11 +232,13 @@ int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper, > { > int err; > > + mutex_lock(&fb_helper->lock); > mutex_lock(&fb_helper->dev->mode_config.mutex); > > err = __drm_fb_helper_remove_one_connector(fb_helper, connector); > > mutex_unlock(&fb_helper->dev->mode_config.mutex); > + mutex_unlock(&fb_helper->lock); > > return err; > } > @@ -478,16 +487,21 @@ int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper) > if (!drm_fbdev_emulation) > return -ENODEV; > > + mutex_lock(&fb_helper->lock); > drm_modeset_lock_all(dev); > + > ret = restore_fbdev_mode(fb_helper); > > do_delayed = fb_helper->delayed_hotplug; > if (do_delayed) > fb_helper->delayed_hotplug = false; > + > drm_modeset_unlock_all(dev); > + mutex_unlock(&fb_helper->lock); > > if (do_delayed) > drm_fb_helper_hotplug_event(fb_helper); > + > return ret; > } > EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked); > @@ -688,6 +702,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, > spin_lock_init(&helper->dirty_lock); > INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work); > helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0; > + mutex_init(&helper->lock); > helper->funcs = funcs; > helper->dev = dev; > } > @@ -853,6 +868,7 @@ void drm_fb_helper_fini(struct drm_fb_helper *fb_helper) > unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op); > } > > + mutex_destroy(&fb_helper->lock); > drm_fb_helper_crtc_free(fb_helper); > > } > @@ -2273,16 +2289,20 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) > { > struct drm_device *dev = fb_helper->dev; > u32 max_width, max_height; > + int err = 0; > > if (!drm_fbdev_emulation) > return 0; > > + mutex_lock(&fb_helper->lock); > mutex_lock(&fb_helper->dev->mode_config.mutex); > + > if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) { > fb_helper->delayed_hotplug = true; > mutex_unlock(&fb_helper->dev->mode_config.mutex); > - return 0; > + goto unlock; > } > + > DRM_DEBUG_KMS("\n"); > > max_width = fb_helper->fb->width; > @@ -2290,6 +2310,7 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) > > drm_fb_helper_probe_connector_modes(fb_helper, max_width, max_height); > mutex_unlock(&fb_helper->dev->mode_config.mutex); > + mutex_unlock(&fb_helper->lock); > > drm_modeset_lock_all(dev); > drm_setup_crtcs(fb_helper); > @@ -2297,6 +2318,10 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) > drm_fb_helper_set_par(fb_helper->fbdev); > > return 0; > + > +unlock: > + mutex_unlock(&fb_helper->lock); > + return err; > } > EXPORT_SYMBOL(drm_fb_helper_hotplug_event); > > diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h > index 5b4aa35026a3..7739be08ebca 100644 > --- a/include/drm/drm_fb_helper.h > +++ b/include/drm/drm_fb_helper.h > @@ -198,6 +198,11 @@ struct drm_fb_helper { > struct work_struct dirty_work; > > /** > + * Top-level FB helper lock. > + */ need to add @lock: in the above comment, otherwise kerneldoc will still complain about the lack of comment for this new member. -Daniel > + struct mutex lock; > + > + /** > * @kernel_fb_list: > * > * Entry on the global kernel_fb_helper_list, used for kgdb entry/exit. > -- > 2.8.3 >
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 252c7557bdb5..f7722bcb0064 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -105,6 +105,7 @@ static int __drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, if (!drm_fbdev_emulation) return 0; + WARN_ON(!mutex_is_locked(&fb_helper->lock)); WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex)); count = fb_helper->connector_count + 1; @@ -127,6 +128,7 @@ static int __drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, drm_connector_reference(connector); conn->connector = connector; fb_helper->connector_info[fb_helper->connector_count++] = conn; + return 0; } @@ -135,11 +137,13 @@ int drm_fb_helper_add_one_connector(struct drm_fb_helper *fb_helper, { int err; + mutex_lock(&fb_helper->lock); mutex_lock(&fb_helper->dev->mode_config.mutex); err = __drm_fb_helper_add_one_connector(fb_helper, connector); mutex_unlock(&fb_helper->dev->mode_config.mutex); + mutex_unlock(&fb_helper->lock); return err; } @@ -168,6 +172,7 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) if (!drm_fbdev_emulation) return 0; + mutex_lock(&fb_helper->lock); mutex_lock(&dev->mode_config.mutex); drm_for_each_connector(connector, dev) { @@ -184,6 +189,7 @@ int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper) } mutex_unlock(&dev->mode_config.mutex); + mutex_unlock(&fb_helper->lock); return ret; } @@ -198,6 +204,7 @@ static int __drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper, if (!drm_fbdev_emulation) return 0; + WARN_ON(!mutex_is_locked(&fb_helper->lock)); WARN_ON(!mutex_is_locked(&fb_helper->dev->mode_config.mutex)); for (i = 0; i < fb_helper->connector_count; i++) { @@ -225,11 +232,13 @@ int drm_fb_helper_remove_one_connector(struct drm_fb_helper *fb_helper, { int err; + mutex_lock(&fb_helper->lock); mutex_lock(&fb_helper->dev->mode_config.mutex); err = __drm_fb_helper_remove_one_connector(fb_helper, connector); mutex_unlock(&fb_helper->dev->mode_config.mutex); + mutex_unlock(&fb_helper->lock); return err; } @@ -478,16 +487,21 @@ int drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper) if (!drm_fbdev_emulation) return -ENODEV; + mutex_lock(&fb_helper->lock); drm_modeset_lock_all(dev); + ret = restore_fbdev_mode(fb_helper); do_delayed = fb_helper->delayed_hotplug; if (do_delayed) fb_helper->delayed_hotplug = false; + drm_modeset_unlock_all(dev); + mutex_unlock(&fb_helper->lock); if (do_delayed) drm_fb_helper_hotplug_event(fb_helper); + return ret; } EXPORT_SYMBOL(drm_fb_helper_restore_fbdev_mode_unlocked); @@ -688,6 +702,7 @@ void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, spin_lock_init(&helper->dirty_lock); INIT_WORK(&helper->dirty_work, drm_fb_helper_dirty_work); helper->dirty_clip.x1 = helper->dirty_clip.y1 = ~0; + mutex_init(&helper->lock); helper->funcs = funcs; helper->dev = dev; } @@ -853,6 +868,7 @@ void drm_fb_helper_fini(struct drm_fb_helper *fb_helper) unregister_sysrq_key('v', &sysrq_drm_fb_helper_restore_op); } + mutex_destroy(&fb_helper->lock); drm_fb_helper_crtc_free(fb_helper); } @@ -2273,16 +2289,20 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) { struct drm_device *dev = fb_helper->dev; u32 max_width, max_height; + int err = 0; if (!drm_fbdev_emulation) return 0; + mutex_lock(&fb_helper->lock); mutex_lock(&fb_helper->dev->mode_config.mutex); + if (!fb_helper->fb || !drm_fb_helper_is_bound(fb_helper)) { fb_helper->delayed_hotplug = true; mutex_unlock(&fb_helper->dev->mode_config.mutex); - return 0; + goto unlock; } + DRM_DEBUG_KMS("\n"); max_width = fb_helper->fb->width; @@ -2290,6 +2310,7 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) drm_fb_helper_probe_connector_modes(fb_helper, max_width, max_height); mutex_unlock(&fb_helper->dev->mode_config.mutex); + mutex_unlock(&fb_helper->lock); drm_modeset_lock_all(dev); drm_setup_crtcs(fb_helper); @@ -2297,6 +2318,10 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper) drm_fb_helper_set_par(fb_helper->fbdev); return 0; + +unlock: + mutex_unlock(&fb_helper->lock); + return err; } EXPORT_SYMBOL(drm_fb_helper_hotplug_event); diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h index 5b4aa35026a3..7739be08ebca 100644 --- a/include/drm/drm_fb_helper.h +++ b/include/drm/drm_fb_helper.h @@ -198,6 +198,11 @@ struct drm_fb_helper { struct work_struct dirty_work; /** + * Top-level FB helper lock. + */ + struct mutex lock; + + /** * @kernel_fb_list: * * Entry on the global kernel_fb_helper_list, used for kgdb entry/exit.