The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ea497bb92064875497554ee7cdf10df7fb7393fc Mon Sep 17 00:00:00 2001
From: Daniel Vetter daniel.vetter@ffwll.ch Date: Wed, 13 Dec 2017 13:49:36 +0100 Subject: [PATCH] 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....
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index c4dfcbc861a1..9ae236036e32 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -152,14 +152,23 @@ 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); + } }
/** @@ -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); 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 cc78b3d9e5e4..256de7313612 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -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) diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h index a4649c56ca2f..5971577016a2 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> @@ -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) diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index b21e827c5c78..b0ce26d71296 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 @@ 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: *