From 3fb1f62f80a1d249260db5ea9e22c51e52fab9ae Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Thu, 16 Feb 2023 15:06:20 +0100 Subject: drm/fb-helper: Remove drm_fb_helper_unprepare() from drm_fb_helper_fini() Move drm_fb_helper_unprepare() from drm_fb_helper_fini() into the calling fbdev implementation. Avoids a possible stale mutex with generic fbdev code. As indicated by its name, drm_fb_helper_prepare() prepares struct drm_fb_helper before setting up the fbdev support with a call to drm_fb_helper_init(). In legacy fbdev emulation, this happens next to each other. If successful, drm_fb_helper_fini() later tear down the fbdev device and also unprepare via drm_fb_helper_unprepare(). Generic fbdev emulation prepares struct drm_fb_helper immediately after allocating the instance. It only calls drm_fb_helper_init() as part of processing a hotplug event. If the hotplug-handling fails, it runs drm_fb_helper_fini(). This unprepares the fb-helper instance and the next hotplug event runs on stale data. Solve this by moving drm_fb_helper_unprepare() from drm_fb_helper_fini() into the fbdev implementations. Call it right before freeing the fb-helper instance. Fixes: 643231b28380 ("drm/fbdev-generic: Minimize hotplug error handling") Cc: Thomas Zimmermann Cc: Javier Martinez Canillas Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: David Airlie Cc: Daniel Vetter Cc: dri-devel@lists.freedesktop.org Signed-off-by: Thomas Zimmermann Reviewed-by: Daniel Vetter Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20230216140620.17699-1-tzimmermann@suse.de --- drivers/gpu/drm/msm/msm_fbdev.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/gpu/drm/msm') diff --git a/drivers/gpu/drm/msm/msm_fbdev.c b/drivers/gpu/drm/msm/msm_fbdev.c index 915b213f3a5c..c804e5ba682a 100644 --- a/drivers/gpu/drm/msm/msm_fbdev.c +++ b/drivers/gpu/drm/msm/msm_fbdev.c @@ -170,6 +170,7 @@ struct drm_fb_helper *msm_fbdev_init(struct drm_device *dev) fini: drm_fb_helper_fini(helper); fail: + drm_fb_helper_unprepare(helper); kfree(fbdev); return NULL; } @@ -196,6 +197,7 @@ void msm_fbdev_free(struct drm_device *dev) drm_framebuffer_remove(fbdev->fb); } + drm_fb_helper_unprepare(helper); kfree(fbdev); priv->fbdev = NULL; -- cgit