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drm: prevent double-(un)registration for connectors 

If we're unlucky then the registration from a hotplugged connector
might race with the final registration step on driver load. And since
MST topology discover is asynchronous that's even somewhat likely.

v2: Also update the kerneldoc for @registered!

v3: Review from Chris:
- Improve kerneldoc for late_register/early_unregister callbacks.
- Use mutex_destroy.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161218133545.2106-1-daniel.vetter@ffwll.ch
(cherry picked from commit e73ab00e9a)
This commit is contained in:
Daniel Vetter 2016-12-18 14:35:45 +01:00
parent 566cf877a1
commit 4e5b54f127
2 changed files with 30 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/gpu/drm/drm_connector.c
View File

@ -225,6 +225,7 @@ int drm_connector_init(struct drm_device *dev,
INIT_LIST_HEAD(&connector->probed_modes);
INIT_LIST_HEAD(&connector->modes);
mutex_init(&connector->mutex);
connector->edid_blob_ptr = NULL;
connector->status = connector_status_unknown;
@ -359,6 +360,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
connector->funcs->atomic_destroy_state(connector,
connector->state);
mutex_destroy(&connector->mutex);
memset(connector, 0, sizeof(*connector));
}
EXPORT_SYMBOL(drm_connector_cleanup);
@ -374,14 +377,15 @@ EXPORT_SYMBOL(drm_connector_cleanup);
*/
int drm_connector_register(struct drm_connector *connector)
{
int ret;
int ret = 0;
mutex_lock(&connector->mutex);
if (connector->registered)
return 0;
goto unlock;
ret = drm_sysfs_connector_add(connector);
if (ret)
return ret;
goto unlock;
ret = drm_debugfs_connector_add(connector);
if (ret) {
@ -397,12 +401,14 @@ int drm_connector_register(struct drm_connector *connector)
drm_mode_object_register(connector->dev, &connector->base);
connector->registered = true;
return 0;
goto unlock;
err_debugfs:
drm_debugfs_connector_remove(connector);
err_sysfs:
drm_sysfs_connector_remove(connector);
unlock:
mutex_unlock(&connector->mutex);
return ret;
}
EXPORT_SYMBOL(drm_connector_register);
@ -415,8 +421,11 @@ EXPORT_SYMBOL(drm_connector_register);
*/
void drm_connector_unregister(struct drm_connector *connector)
{
if (!connector->registered)
mutex_lock(&connector->mutex);
if (!connector->registered) {
mutex_unlock(&connector->mutex);
return;
}
if (connector->funcs->early_unregister)
connector->funcs->early_unregister(connector);
@ -425,6 +434,7 @@ void drm_connector_unregister(struct drm_connector *connector)
drm_debugfs_connector_remove(connector);
connector->registered = false;
mutex_unlock(&connector->mutex);
}
EXPORT_SYMBOL(drm_connector_unregister);

16
include/drm/drm_connector.h
View File

@ -381,6 +381,8 @@ struct drm_connector_funcs {
* core drm connector interfaces. Everything added from this callback
* should be unregistered in the early_unregister callback.
*
* This is called while holding drm_connector->mutex.
*
* Returns:
*
* 0 on success, or a negative error code on failure.
@ -395,6 +397,8 @@ struct drm_connector_funcs {
* late_register(). It is called from drm_connector_unregister(),
* early in the driver unload sequence to disable userspace access
* before data structures are torndown.
*
* This is called while holding drm_connector->mutex.
*/
void (*early_unregister)(struct drm_connector *connector);
@ -559,7 +563,6 @@ struct drm_cmdline_mode {
* @interlace_allowed: can this connector handle interlaced modes?
* @doublescan_allowed: can this connector handle doublescan?
* @stereo_allowed: can this connector handle stereo modes?
* @registered: is this connector exposed (registered) with userspace?
* @modes: modes available on this connector (from fill_modes() + user)
* @status: one of the drm_connector_status enums (connected, not, or unknown)
* @probed_modes: list of modes derived directly from the display
@ -607,6 +610,13 @@ struct drm_connector {
char *name;
/**
* @mutex: Lock for general connector state, but currently only protects
* @registered. Most of the connector state is still protected by the
* mutex in &drm_mode_config.
*/
struct mutex mutex;
/**
* @index: Compacted connector index, which matches the position inside
* the mode_config.list for drivers not supporting hot-add/removing. Can
@ -620,6 +630,10 @@ struct drm_connector {
bool interlace_allowed;
bool doublescan_allowed;
bool stereo_allowed;
/**
* @registered: Is this connector exposed (registered) with userspace?
* Protected by @mutex.
*/
bool registered;
struct list_head modes; /* list of modes on this connector */