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Commit ea497bb9 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

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: a703c550 ("drm: safely free connectors from connector_iter")
Fixes: 613051da ("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+: 613051da ("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: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171213124936.17914-1-daniel.vetter@ffwll.ch
parent 4b4df570

drivers/gpu/drm/drm_connector.c

+35 −15
Original line number Original line Diff line number Diff line
@@ -152,15 +152,24 @@ static void drm_connector_free(struct kref *kref) 
	connector->funcs->destroy(connector);

	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 =

	struct drm_connector *connector, *n;

		container_of(work, struct drm_connector, free_work);

	struct drm_device *dev =

	struct drm_device *dev = connector->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);

		drm_mode_object_unregister(dev, &connector->base);

		connector->funcs->destroy(connector);

		connector->funcs->destroy(connector);

	}

	}

}





/**

/**

 * drm_connector_init - Init a preallocated connector

 * drm_connector_init - Init a preallocated connector
@@ -191,8 +200,6 @@ int drm_connector_init(struct drm_device *dev, 
	if (ret)

	if (ret)

		return ret;

		return ret;





	INIT_WORK(&connector->free_work, drm_connector_free_work_fn);



	connector->base.properties = &connector->properties;

	connector->base.properties = &connector->properties;

	connector->dev = dev;

	connector->dev = dev;

	connector->funcs = funcs;

	connector->funcs = funcs;
@@ -547,10 +554,17 @@ EXPORT_SYMBOL(drm_connector_list_iter_begin); 
 * actually release the connector when dropping our final reference.

 * actually release the connector when dropping our final reference.

 */

 */

static void

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))

	struct drm_mode_config *config = &conn->dev->mode_config;

		schedule_work(&conn->free_work);



	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 */

		/* loop until it's not a zombie connector */

	} while (!kref_get_unless_zero(&iter->conn->base.refcount));

	} while (!kref_get_unless_zero(&iter->conn->base.refcount));

	spin_unlock_irqrestore(&config->connector_list_lock, flags);





	if (old_conn)

	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;

	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)

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;

	iter->dev = NULL;

	if (iter->conn)

	if (iter->conn) {

		drm_connector_put_safe(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_);

	lock_release(&connector_list_iter_dep_map, 0, _RET_IP_);

}

}

EXPORT_SYMBOL(drm_connector_list_iter_end);

EXPORT_SYMBOL(drm_connector_list_iter_end);

drivers/gpu/drm/drm_crtc_internal.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -142,6 +142,7 @@ int drm_mode_connector_set_obj_prop(struct drm_mode_object *obj, 
				    uint64_t value);

				    uint64_t value);

int drm_connector_create_standard_properties(struct drm_device *dev);

int drm_connector_create_standard_properties(struct drm_device *dev);

const char *drm_get_connector_force_name(enum drm_connector_force force);

const char *drm_get_connector_force_name(enum drm_connector_force force);

void drm_connector_free_work_fn(struct work_struct *work);





/* IOCTL */

/* IOCTL */

int drm_mode_connector_property_set_ioctl(struct drm_device *dev,

int drm_mode_connector_property_set_ioctl(struct drm_device *dev,

drivers/gpu/drm/drm_mode_config.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -382,6 +382,9 @@ void drm_mode_config_init(struct drm_device *dev) 
	ida_init(&dev->mode_config.connector_ida);

	ida_init(&dev->mode_config.connector_ida);

	spin_lock_init(&dev->mode_config.connector_list_lock);

	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);

	drm_mode_create_standard_properties(dev);





	/* Just to be sure */

	/* Just to be sure */
@@ -432,7 +435,7 @@ void drm_mode_config_cleanup(struct drm_device *dev) 
	}

	}

	drm_connector_list_iter_end(&conn_iter);

	drm_connector_list_iter_end(&conn_iter);

	/* connector_iter drops references in a work item. */

	/* 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))) {

	if (WARN_ON(!list_empty(&dev->mode_config.connector_list))) {

		drm_connector_list_iter_begin(dev, &conn_iter);

		drm_connector_list_iter_begin(dev, &conn_iter);

		drm_for_each_connector_iter(connector, &conn_iter)

		drm_for_each_connector_iter(connector, &conn_iter)

include/drm/drm_connector.h

+6 −4
Original line number Original line Diff line number Diff line
@@ -24,6 +24,7 @@ 
#define __DRM_CONNECTOR_H__

#define __DRM_CONNECTOR_H__





#include <linux/list.h>

#include <linux/list.h>

#include <linux/llist.h>

#include <linux/ctype.h>

#include <linux/ctype.h>

#include <linux/hdmi.h>

#include <linux/hdmi.h>

#include <drm/drm_mode_object.h>

#include <drm/drm_mode_object.h>
@@ -918,12 +919,13 @@ struct drm_connector { 
	uint16_t tile_h_size, tile_v_size;

	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

	 * List used only by &drm_connector_iter to be able to clean up a

	 * connector from any context.

	 * 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)

#define obj_to_connector(x) container_of(x, struct drm_connector, base)

include/drm/drm_mode_config.h

+17 −1
Original line number Original line Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/types.h>

#include <linux/types.h>

#include <linux/idr.h>

#include <linux/idr.h>

#include <linux/workqueue.h>

#include <linux/workqueue.h>

#include <linux/llist.h>





#include <drm/drm_modeset_lock.h>

#include <drm/drm_modeset_lock.h>
@@ -393,7 +394,7 @@ struct drm_mode_config { 




	/**

	/**

	 * @connector_list_lock: Protects @num_connector and

	 * @connector_list_lock: Protects @num_connector and

	 * @connector_list.

	 * @connector_list and @connector_free_list.

	 */

	 */

	spinlock_t connector_list_lock;

	spinlock_t connector_list_lock;

	/**

	/**
@@ -413,6 +414,21 @@ struct drm_mode_config { 
	 * &struct drm_connector_list_iter to walk this list.

	 * &struct drm_connector_list_iter to walk this list.

	 */

	 */

	struct list_head connector_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:

	 * @num_encoder:

	 *

	 *