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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: a703c55004 ("drm: safely free connectors from connector_iter")
Fixes: 613051dac4 ("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+: 613051dac4 ("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
This commit is contained in:
Daniel Vetter 2017-12-13 13:49:36 +01:00
parent 4b4df570b4
commit ea497bb920
5 changed files with 63 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
drivers/gpu/drm/drm_connector.c
View File

@ -152,15 +152,24 @@ 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;
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);
}
}
/**
* drm_connector_init - Init a preallocated connector
@ -191,8 +200,6 @@ 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;
@ -547,10 +554,17 @@ 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);
}
/**
@ -582,10 +596,10 @@ 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;
}
@ -602,9 +616,15 @@ 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);

1
drivers/gpu/drm/drm_crtc_internal.h
View File

@ -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,

5
drivers/gpu/drm/drm_mode_config.c
View File

@ -382,6 +382,9 @@ 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_llist_head(&dev->mode_config.connector_free_list);
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 +435,7 @@ 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)

10
include/drm/drm_connector.h
View File

@ -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>
@ -918,12 +919,13 @@ 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)

18
include/drm/drm_mode_config.h
View File

@ -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 @@ struct drm_mode_config {
/**
* @connector_list_lock: Protects @num_connector and
* @connector_list.
* @connector_list and @connector_free_list.
*/
spinlock_t connector_list_lock;
/**
@ -413,6 +414,21 @@ 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:
*