Merge branch 'drm-kms-locking' of git://people.freedesktop.org/~danvet/drm-intel into drm-next

The aim of this locking rework is that ioctls which a compositor should be
might call for every frame (set_cursor, page_flip, addfb, rmfb and
getfb/create_handle) should not be able to block on kms background
activities like output detection. And since each EDID read takes about
25ms (in the best case), that always means we'll drop at least one frame.

The solution is to add per-crtc locking for these ioctls, and restrict
background activities to only use the global lock. Change-the-world type
of events (modeset, dpms, ...) need to grab all locks.

Two tricky parts arose in the conversion:
- A lot of current code assumes that a kms fb object can't disappear while
  holding the global lock, since the current code serializes fb
  destruction with it. Hence proper lifetime management using the already
  created refcounting for fbs need to be instantiated for all ioctls and
  interfaces/users.

- The rmfb ioctl removes the to-be-deleted fb from all active users. But
  unconditionally taking the global kms lock to do so introduces an
  unacceptable potential stall point. And obviously changing the userspace
  abi isn't on the table, either. Hence this conversion opportunistically
  checks whether the rmfb ioctl holds the very last reference, which
  guarantees that the fb isn't in active use on any crtc or plane (thanks
  to the conversion to the new lifetime rules using proper refcounting).
  Only if this is not the case will the code go through the slowpath and
  grab all modeset locks. Sane compositors will never hit this path and so
  avoid the stall, but userspace relying on these semantics will also not
  break.

All these cases are exercised by the newly added subtests for the i-g-t
kms_flip, tested on a machine where a full detect cycle takes around 100
ms.  It works, and no frames are dropped any more with these patches
applied.  kms_flip also contains a special case to exercise the
above-describe rmfb slowpath.

* 'drm-kms-locking' of git://people.freedesktop.org/~danvet/drm-intel: (335 commits)
  drm/fb_helper: check whether fbcon is bound
  drm/doc: updates for new framebuffer lifetime rules
  drm: don't hold crtc mutexes for connector ->detect callbacks
  drm: only grab the crtc lock for pageflips
  drm: optimize drm_framebuffer_remove
  drm/vmwgfx: add proper framebuffer refcounting
  drm/i915: dump refcount into framebuffer debugfs file
  drm: refcounting for crtc framebuffers
  drm: refcounting for sprite framebuffers
  drm: fb refcounting for dirtyfb_ioctl
  drm: don't take modeset locks in getfb ioctl
  drm: push modeset_lock_all into ->fb_create driver callbacks
  drm: nest modeset locks within fpriv->fbs_lock
  drm: reference framebuffers which are on the idr
  drm: revamp framebuffer cleanup interfaces
  drm: create drm_framebuffer_lookup
  drm: revamp locking around fb creation/destruction
  drm: only take the crtc lock for ->cursor_move
  drm: only take the crtc lock for ->cursor_set
  drm: add per-crtc locks
  ...

3 files changed, 44 insertions, 1 deletions

diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index fad21c9..e74731c 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -446,7 +446,15 @@ struct drm_file {
 	int is_master; /* this file private is a master for a minor */
 	struct drm_master *master; /* master this node is currently associated with
 				      N.B. not always minor->master */
+
+	/**
+	 * fbs - List of framebuffers associated with this file.
+	 *
+	 * Protected by fbs_lock. Note that the fbs list holds a reference on
+	 * the fb object to prevent it from untimely disappearing.
+	 */
 	struct list_head fbs;
+	struct mutex fbs_lock;
 
 	wait_queue_head_t event_wait;
 	struct list_head event_list;
@@ -1276,6 +1284,11 @@ static inline int drm_device_is_unplugged(struct drm_device *dev)
 	return ret;
 }
 
+static inline bool drm_modeset_is_locked(struct drm_device *dev)
+{
+	return mutex_is_locked(&dev->mode_config.mutex);
+}
+
 /******************************************************************/
 /** \name Internal function definitions */
 /*@{*/
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 00d78b5..66b2732 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -254,6 +254,10 @@ struct drm_framebuffer {
 	 * userspace perspective.
 	 */
 	struct kref refcount;
+	/*
+	 * Place on the dev->mode_config.fb_list, access protected by
+	 * dev->mode_config.fb_lock.
+	 */
 	struct list_head head;
 	struct drm_mode_object base;
 	const struct drm_framebuffer_funcs *funcs;
@@ -390,6 +394,15 @@ struct drm_crtc {
 	struct drm_device *dev;
 	struct list_head head;
 
+	/**
+	 * crtc mutex
+	 *
+	 * This provides a read lock for the overall crtc state (mode, dpms
+	 * state, ...) and a write lock for everything which can be update
+	 * without a full modeset (fb, cursor data, ...)
+	 */
+	struct mutex mutex;
+
 	struct drm_mode_object base;
 
 	/* framebuffer the connector is currently bound to */
@@ -771,8 +784,18 @@ struct drm_mode_config {
 	struct mutex idr_mutex; /* for IDR management */
 	struct idr crtc_idr; /* use this idr for all IDs, fb, crtc, connector, modes - just makes life easier */
 	/* this is limited to one for now */
+
+
+	/**
+	 * fb_lock - mutex to protect fb state
+	 *
+	 * Besides the global fb list his also protects the fbs list in the
+	 * file_priv
+	 */
+	struct mutex fb_lock;
 	int num_fb;
 	struct list_head fb_list;
+
 	int num_connector;
 	struct list_head connector_list;
 	int num_encoder;
@@ -842,6 +865,9 @@ struct drm_prop_enum_list {
 	char *name;
 };
 
+extern void drm_modeset_lock_all(struct drm_device *dev);
+extern void drm_modeset_unlock_all(struct drm_device *dev);
+
 extern int drm_crtc_init(struct drm_device *dev,
 			 struct drm_crtc *crtc,
 			 const struct drm_crtc_funcs *funcs);
@@ -932,10 +958,13 @@ extern void drm_framebuffer_set_object(struct drm_device *dev,
 extern int drm_framebuffer_init(struct drm_device *dev,
 				struct drm_framebuffer *fb,
 				const struct drm_framebuffer_funcs *funcs);
+extern struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev,
+						      uint32_t id);
 extern void drm_framebuffer_unreference(struct drm_framebuffer *fb);
 extern void drm_framebuffer_reference(struct drm_framebuffer *fb);
 extern void drm_framebuffer_remove(struct drm_framebuffer *fb);
 extern void drm_framebuffer_cleanup(struct drm_framebuffer *fb);
+extern void drm_framebuffer_unregister_private(struct drm_framebuffer *fb);
 extern int drmfb_probe(struct drm_device *dev, struct drm_crtc *crtc);
 extern int drmfb_remove(struct drm_device *dev, struct drm_framebuffer *fb);
 extern void drm_crtc_probe_connector_modes(struct drm_device *dev, int maxX, int maxY);
@@ -985,6 +1014,7 @@ extern int drm_mode_getcrtc(struct drm_device *dev,
 			    void *data, struct drm_file *file_priv);
 extern int drm_mode_getconnector(struct drm_device *dev,
 			      void *data, struct drm_file *file_priv);
+extern int drm_mode_set_config_internal(struct drm_mode_set *set);
 extern int drm_mode_setcrtc(struct drm_device *dev,
 			    void *data, struct drm_file *file_priv);
 extern int drm_mode_getplane(struct drm_device *dev,
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index 9b991f9..88591ef 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -70,7 +70,7 @@ struct drm_mm {
 	unsigned long scan_color;
 	unsigned long scan_size;
 	unsigned long scan_hit_start;
-	unsigned scan_hit_size;
+	unsigned long scan_hit_end;
 	unsigned scanned_blocks;
 	unsigned long scan_start;
 	unsigned long scan_end;