diff options
| author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2020-12-16 12:53:22 +0100 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2024-01-08 14:01:49 +0100 |
| commit | fb95899e695a8699f8b16e6149dbab845aa3fb24 (patch) | |
| tree | e4b7aadc3ca8cda65a5ca2760ec115d2a075795f | |
| parent | 9094207bb7b8e8bc37a22aff8dedb887a2c3e218 (diff) | |
drm/fb-helper: Try to protect cleanup against delayed setup
Some vague evidences suggests this can go wrong. Try to prevent it by
holding the right mutex and clearing ->deferred_setup to make sure we
later on don't accidentally try to re-register the fbdev when the
driver thought it had it all cleaned up already.
v2: I realized that this is fundamentally butchered, and CI complained
about lockdep splats. So limit the critical section again and just add
a few notes what the proper fix is.
References: https://intel-gfx-ci.01.org/tree/linux-next/next-20201215/fi-byt-j1900/igt@i915_pm_rpm@module-reload.html
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
| -rw-r--r-- | drivers/gpu/drm/drm_fb_helper.c | 6 | ||||
| -rw-r--r-- | drivers/gpu/drm/drm_fbdev_generic.c | 5 |
2 files changed, 11 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index b05e5bb8d58f..466a2a5e42be 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -569,6 +569,9 @@ EXPORT_SYMBOL(drm_fb_helper_release_info); * A wrapper around unregister_framebuffer, to release the fb_info * framebuffer device. This must be called before releasing all resources for * @fb_helper by calling drm_fb_helper_fini(). + * + * Note that this is fundamentally racy on hotunload because it doen't handle + * open fbdev file descriptors at all. Use drm_fbdev_generic_setup() instead. */ void drm_fb_helper_unregister_info(struct drm_fb_helper *fb_helper) { @@ -582,6 +585,9 @@ EXPORT_SYMBOL(drm_fb_helper_unregister_info); * @fb_helper: driver-allocated fbdev helper, can be NULL * * This cleans up all remaining resources associated with @fb_helper. + * + * Note that this is fundamentally racy on hotunload because it doen't handle + * open fbdev file descriptors at all. Use drm_fbdev_generic_setup() instead. */ void drm_fb_helper_fini(struct drm_fb_helper *fb_helper) { diff --git a/drivers/gpu/drm/drm_fbdev_generic.c b/drivers/gpu/drm/drm_fbdev_generic.c index d647d89764cb..7d281c29faf6 100644 --- a/drivers/gpu/drm/drm_fbdev_generic.c +++ b/drivers/gpu/drm/drm_fbdev_generic.c @@ -244,7 +244,12 @@ static void drm_fbdev_generic_client_unregister(struct drm_client_dev *client) { struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client); + mutex_lock(&fb_helper->lock); + fb_helper->deferred_setup = false; + mutex_unlock(&fb_helper->lock); + if (fb_helper->info) { + /* drm_fbdev_fb_destroy() takes care of cleanup */ drm_fb_helper_unregister_info(fb_helper); } else { drm_client_release(&fb_helper->client); |