From a63c863e6d1fac6e8e93f3a72df649cd5655e6e3 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 17 Sep 2019 14:09:35 +0200 Subject: [PATCH 3963/4256] drm/kms: Duct-tape for mode object lifetime checks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 4f5368b5541a902f6596558b05f5c21a9770dd32 Author: Daniel Vetter Date: Fri Jun 14 08:17:23 2019 +0200 drm/kms: Catch mode_object lifetime errors uncovered a bit a mess in dp drivers. Most drivers (from a quick look, all except i915) register all the dp stuff in their init code, which is too early. With CONFIG_DRM_DP_AUX_CHARDEV this will blow up, because drm_dp_aux_register tries to add a child to a device in sysfs (the connector) which doesn't even exist yet. No one seems to have cared thus far. But with the above change I also moved the setting of dev->registered after the ->load callback, in an attempt to keep old drivers from hitting any WARN_ON backtraces. But that moved radeon.ko from the "working, by accident" to "now also broken" category. Since this is a huge mess I figured a revert would be simplest. But this check has already caught issues in i915: commit 1b9bd09630d4db4827cc04d358a41a16a6bc2cb0 Author: Ville Syrjälä Date: Tue Aug 20 19:16:57 2019 +0300 drm/i915: Do not create a new max_bpc prop for MST connectors Hence I'd like to retain it. Fix the radeon regression by moving the setting of dev->registered back to were it was, and stop the backtraces with an explicit check for dev->driver->load. Everyone else will stay as broken with CONFIG_DRM_DP_AUX_CHARDEV. The next patch will improve the kerneldoc and add a todo entry for this. Fixes: 4f5368b5541a ("drm/kms: Catch mode_object lifetime errors") Cc: Sean Paul Cc: Maarten Lankhorst Reported-by: Michel Dänzer Reviewed-by: Michel Dänzer Tested-by: Michel Dänzer Cc: Michel Dänzer Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20190917120936.7501-1-daniel.vetter@ffwll.ch Signed-off-by: Alex Deucher Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_mode_object.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c index fcb0ab0abb75..126750583415 100644 --- a/drivers/gpu/drm/drm_mode_object.c +++ b/drivers/gpu/drm/drm_mode_object.c @@ -37,6 +37,8 @@ int __drm_mode_object_add(struct drm_device *dev, struct drm_mode_object *obj, { int ret; + WARN_ON(!dev->driver->load && dev->registered && !obj_free_cb); + mutex_lock(&dev->mode_config.idr_mutex); ret = idr_alloc(&dev->mode_config.crtc_idr, register_obj ? obj : NULL, 1, 0, GFP_KERNEL); if (ret >= 0) { @@ -96,6 +98,8 @@ void drm_mode_object_register(struct drm_device *dev, void drm_mode_object_unregister(struct drm_device *dev, struct drm_mode_object *object) { + WARN_ON(!dev->driver->load && dev->registered && !object->free_cb); + mutex_lock(&dev->mode_config.idr_mutex); if (object->id) { idr_remove(&dev->mode_config.crtc_idr, object->id); -- 2.17.1