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@xxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+: 613051dac40d ("drm: locking&new iterators for connector_list"
Cc: <stable@xxxxxxxxxxxxxxx> # v4.11+
Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Javier Martinez Canillas <javier@xxxxxxxxxxxx>
Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Cc: Guillaume Tucker <guillaume.tucker@xxxxxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxxxx>
Cc: Matt Hart <matthew.hart@xxxxxxxxxx>
Cc: Thierry Escande <thierry.escande@xxxxxxxxxxxxxxx>
Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Cc: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
---
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.
*/
spinlock_t connector_list_lock;
/**
@@ -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:
*
--
2.15.1