drm: rework delayed connector cleanup in connector_iter
PROBE_DEFER also uses system_wq to reprobe drivers, which means when
that again fails, and we try to flush the overall system_wq (to get
all the delayed connectore cleanup work_struct completed), we
deadlock.
Fix this by using just a single cleanup work, so that we can only
flush that one and don't block on anything else. That means a free
list plus locking, a standard pattern.
v2:
- Correctly free connectors only on last ref. Oops (Chris).
- use llist_head/node (Chris).
v3
- Add init_llist_head (Chris).
Fixes: a703c55004e1 ("drm: safely free connectors from connector_iter")
Fixes: 613051dac40d ("drm: locking&new iterators for connector_list")
Cc: Ben Widawsky <ben@bwidawsk.net>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: <stable@vger.kernel.org> # v4.11+: 613051dac40d ("drm: locking&new iterators for connector_list"
Cc: <stable@vger.kernel.org> # v4.11+
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Javier Martinez Canillas <javier@dowhile0.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Matt Hart <matthew.hart@linaro.org>
Cc: Thierry Escande <thierry.escande@collabora.co.uk>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171213124936.17914-1-daniel.vetter@ffwll.ch
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index b21e827..b0ce26d 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -27,6 +27,7 @@
#include <linux/types.h>
#include <linux/idr.h>
#include <linux/workqueue.h>
+#include <linux/llist.h>
#include <drm/drm_modeset_lock.h>
@@ -393,7 +394,7 @@
/**
* @connector_list_lock: Protects @num_connector and
- * @connector_list.
+ * @connector_list and @connector_free_list.
*/
spinlock_t connector_list_lock;
/**
@@ -414,6 +415,21 @@
*/
struct list_head connector_list;
/**
+ * @connector_free_list:
+ *
+ * List of connector objects linked with &drm_connector.free_head.
+ * Protected by @connector_list_lock. Used by
+ * drm_for_each_connector_iter() and
+ * &struct drm_connector_list_iter to savely free connectors using
+ * @connector_free_work.
+ */
+ struct llist_head connector_free_list;
+ /**
+ * @connector_free_work: Work to clean up @connector_free_list.
+ */
+ struct work_struct connector_free_work;
+
+ /**
* @num_encoder:
*
* Number of encoders on this device. This is invariant over the