Hi Daniel,
On 2017-12-13 13:49, Daniel Vetter wrote:
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).
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 Signed-off-by: Daniel Vetter daniel.vetter@intel.com
This one works fine and fixes deadlock in my test environment.
Tested-by: Marek Szyprowski m.szyprowski@samsung.com
drivers/gpu/drm/drm_connector.c | 50 ++++++++++++++++++++++++++----------- drivers/gpu/drm/drm_crtc_internal.h | 1 + drivers/gpu/drm/drm_mode_config.c | 4 ++- include/drm/drm_connector.h | 10 +++++--- include/drm/drm_mode_config.h | 18 ++++++++++++- 5 files changed, 62 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index 0b7e0974e6da..3f53f127e1f2 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -153,14 +153,23 @@ static void drm_connector_free(struct kref *kref) connector->funcs->destroy(connector); } -static void drm_connector_free_work_fn(struct work_struct *work) +void drm_connector_free_work_fn(struct work_struct *work) {
- struct drm_connector *connector =
container_of(work, struct drm_connector, free_work);- struct drm_device *dev = connector->dev;
- struct drm_connector *connector, *n;
- struct drm_device *dev =
container_of(work, struct drm_device, mode_config.connector_free_work);- struct drm_mode_config *config = &dev->mode_config;
- unsigned long flags;
- struct llist_node *freed;
- drm_mode_object_unregister(dev, &connector->base);
- connector->funcs->destroy(connector);
- spin_lock_irqsave(&config->connector_list_lock, flags);
- freed = llist_del_all(&config->connector_free_list);
- spin_unlock_irqrestore(&config->connector_list_lock, flags);
- llist_for_each_entry_safe(connector, n, freed, free_node) {
drm_mode_object_unregister(dev, &connector->base);connector->funcs->destroy(connector);- } }
/** @@ -192,8 +201,6 @@ int drm_connector_init(struct drm_device *dev, if (ret) return ret;
- INIT_WORK(&connector->free_work, drm_connector_free_work_fn);
- connector->base.properties = &connector->properties; connector->dev = dev; connector->funcs = funcs;
@@ -550,10 +557,17 @@ EXPORT_SYMBOL(drm_connector_list_iter_begin);
- actually release the connector when dropping our final reference.
*/ static void -drm_connector_put_safe(struct drm_connector *conn) +__drm_connector_put_safe(struct drm_connector *conn) {
- if (refcount_dec_and_test(&conn->base.refcount.refcount))
schedule_work(&conn->free_work);
- struct drm_mode_config *config = &conn->dev->mode_config;
- lockdep_assert_held(&config->connector_list_lock);
- if (!refcount_dec_and_test(&conn->base.refcount.refcount))
return;- llist_add(&conn->free_node, &config->connector_free_list);
- schedule_work(&config->connector_free_work); }
/** @@ -585,10 +599,10 @@ drm_connector_list_iter_next(struct drm_connector_list_iter *iter) /* loop until it's not a zombie connector */ } while (!kref_get_unless_zero(&iter->conn->base.refcount));
- spin_unlock_irqrestore(&config->connector_list_lock, flags);
if (old_conn)
drm_connector_put_safe(old_conn);
__drm_connector_put_safe(old_conn);- spin_unlock_irqrestore(&config->connector_list_lock, flags);
return iter->conn; } @@ -605,9 +619,15 @@ EXPORT_SYMBOL(drm_connector_list_iter_next); */ void drm_connector_list_iter_end(struct drm_connector_list_iter *iter) {
- struct drm_mode_config *config = &iter->dev->mode_config;
- unsigned long flags;
- iter->dev = NULL;
- if (iter->conn)
drm_connector_put_safe(iter->conn);
- if (iter->conn) {
spin_lock_irqsave(&config->connector_list_lock, flags);__drm_connector_put_safe(iter->conn);spin_unlock_irqrestore(&config->connector_list_lock, flags);- } lock_release(&connector_list_iter_dep_map, 0, _RET_IP_); } EXPORT_SYMBOL(drm_connector_list_iter_end);
diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h index 9ebb8841778c..af00f42ba269 100644 --- a/drivers/gpu/drm/drm_crtc_internal.h +++ b/drivers/gpu/drm/drm_crtc_internal.h @@ -142,6 +142,7 @@ int drm_mode_connector_set_obj_prop(struct drm_mode_object *obj, uint64_t value); int drm_connector_create_standard_properties(struct drm_device *dev); const char *drm_get_connector_force_name(enum drm_connector_force force); +void drm_connector_free_work_fn(struct work_struct *work); /* IOCTL */ int drm_mode_connector_property_set_ioctl(struct drm_device *dev, diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index 6ffe952142e6..7681269abe41 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -382,6 +382,8 @@ void drm_mode_config_init(struct drm_device *dev) ida_init(&dev->mode_config.connector_ida); spin_lock_init(&dev->mode_config.connector_list_lock);
- INIT_WORK(&dev->mode_config.connector_free_work, drm_connector_free_work_fn);
- drm_mode_create_standard_properties(dev);
/* Just to be sure */ @@ -432,7 +434,7 @@ void drm_mode_config_cleanup(struct drm_device *dev) } drm_connector_list_iter_end(&conn_iter); /* connector_iter drops references in a work item. */
- flush_scheduled_work();
- flush_work(&dev->mode_config.connector_free_work); if (WARN_ON(!list_empty(&dev->mode_config.connector_list))) { drm_connector_list_iter_begin(dev, &conn_iter); drm_for_each_connector_iter(connector, &conn_iter)
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index ee3155391243..ed38df4ac204 100644 --- a/include/drm/drm_connector.h +++ b/include/drm/drm_connector.h @@ -24,6 +24,7 @@ #define __DRM_CONNECTOR_H__ #include <linux/list.h> +#include <linux/llist.h> #include <linux/ctype.h> #include <linux/hdmi.h> #include <drm/drm_mode_object.h> @@ -966,12 +967,13 @@ struct drm_connector { uint16_t tile_h_size, tile_v_size; /**
* @free_work:
* @free_node:
* Work used only by &drm_connector_iter to be able to clean up a* connector from any context.
* List used only by &drm_connector_iter to be able to clean up a* connector from any context, in conjunction with* &drm_mode_config.connector_free_work.
- struct work_struct free_work;
- struct llist_node free_node; };
#define obj_to_connector(x) container_of(x, struct drm_connector, base) diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index e5f3b43014e1..2cb6f02df64a 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> @@ -402,7 +403,7 @@ struct drm_mode_config { /** * @connector_list_lock: Protects @num_connector and
* @connector_list.
* @connector_list and @connector_free_list.@@ -422,6 +423,21 @@ struct drm_mode_config { * &struct drm_connector_list_iter to walk this list. */ 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:
Best regards