From a915aaa15616e957253766bf53a82ea6a1d53295 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 5 Jun 2014 11:07:20 +0200 Subject: [PATCH] drm: Fix getconnector connection_mutex locking MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit I've fumbled my own idea and enthusiastically wrapped all the getconnector code with the connection_mutex. But we only need it to chase the connector->encoder link. Even there it's not really needed since races with userspace won't matter, but better paranoid and consistent about this stuff. If we grap it everywhere connector probe callbacks can't grab it themselves, which means they'll deadlock. i915 does that for the load detect pipe. Furthermore i915 needs to do a ww dance since we also need to grab the mutex of the load detect crtc. This is a regression from commit d9e3d5709c9db926007485d575b4c21cfc4da9ea Author: Daniel Vetter Date: Thu May 29 23:54:47 2014 +0200 drm: Split connection_mutex out of mode_config.mutex (v3) Cc: Rob Clark Cc: Dave Airlie Cc: Ville Syrjälä Reported-by: Ville Syrjälä Reviewed-by: Rob Clark Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_crtc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index b8cc4fe0a0f7a..fe94cc10cd350 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1838,7 +1838,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, DRM_DEBUG_KMS("[CONNECTOR:%d:?]\n", out_resp->connector_id); mutex_lock(&dev->mode_config.mutex); - drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); connector = drm_connector_find(dev, out_resp->connector_id); if (!connector) { @@ -1872,10 +1871,12 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, out_resp->mm_height = connector->display_info.height_mm; out_resp->subpixel = connector->display_info.subpixel_order; out_resp->connection = connector->status; + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL); if (connector->encoder) out_resp->encoder_id = connector->encoder->base.id; else out_resp->encoder_id = 0; + drm_modeset_unlock(&dev->mode_config.connection_mutex); /* * This ioctl is called twice, once to determine how much space is @@ -1937,7 +1938,6 @@ int drm_mode_getconnector(struct drm_device *dev, void *data, out_resp->count_encoders = encoders_count; out: - drm_modeset_unlock(&dev->mode_config.connection_mutex); mutex_unlock(&dev->mode_config.mutex); return ret; -- 2.39.5