[PATCH 11/34] drm: Convert crtc_idr to XArray

Matthew Wilcox willy at infradead.org
Thu Feb 21 18:41:41 UTC 2019


 - Rename it to 'objects', as requested in todo.rst
 - Also convert leases IDR to XArray as the two are occasionally used by
   the same code (see drm_mode_get_lease_ioctl())
 - Refactor drm_mode_create_lease_ioctl() to create the new drm_master
   early to avoid creating an XArray on the stack and reparenting it
   afterwards.

Signed-off-by: Matthew Wilcox <willy at infradead.org>
---
 Documentation/gpu/todo.rst        |   3 -
 drivers/gpu/drm/drm_auth.c        |   4 +-
 drivers/gpu/drm/drm_lease.c       | 136 ++++++++++++++----------------
 drivers/gpu/drm/drm_mode_config.c |   3 +-
 drivers/gpu/drm/drm_mode_object.c |  47 +++++------
 include/drm/drm_auth.h            |   2 +-
 include/drm/drm_mode_config.h     |   6 +-
 7 files changed, 90 insertions(+), 111 deletions(-)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 14191b64446d..41da7b06195c 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -354,9 +354,6 @@ KMS cleanups
 
 Some of these date from the very introduction of KMS in 2008 ...
 
-- drm_mode_config.crtc_idr is misnamed, since it contains all KMS object. Should
-  be renamed to drm_mode_config.object_idr.
-
 - drm_display_mode doesn't need to be derived from drm_mode_object. That's
   leftovers from older (never merged into upstream) KMS designs where modes
   where set using their ID, including support to add/remove modes.
diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
index 1813507f9b9c..c6967f0b095d 100644
--- a/drivers/gpu/drm/drm_auth.c
+++ b/drivers/gpu/drm/drm_auth.c
@@ -110,7 +110,7 @@ struct drm_master *drm_master_create(struct drm_device *dev)
 	/* initialize the tree of output resource lessees */
 	master->lessor = NULL;
 	master->lessee_id = 0;
-	idr_init(&master->leases);
+	xa_init(&master->leases);
 	xa_init_flags(&master->lessees, XA_FLAGS_ALLOC1);
 
 	return master;
@@ -345,7 +345,7 @@ static void drm_master_destroy(struct kref *kref)
 
 	drm_legacy_master_rmmaps(dev, master);
 
-	idr_destroy(&master->leases);
+	xa_destroy(&master->leases);
 
 	kfree(master->unique);
 	kfree(master);
diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c
index 47830f9ec616..1e88f406c738 100644
--- a/drivers/gpu/drm/drm_lease.c
+++ b/drivers/gpu/drm/drm_lease.c
@@ -20,8 +20,6 @@
 #include <drm/drm_auth.h>
 #include <drm/drm_crtc_helper.h>
 
-static uint64_t drm_lease_idr_object;
-
 /**
  * drm_lease_owner - return ancestor owner drm_master
  * @master: drm_master somewhere within tree of lessees and lessors
@@ -69,7 +67,7 @@ static int _drm_lease_held_master(struct drm_master *master, int id)
 {
 	lockdep_assert_held(&master->dev->mode_config.idr_mutex);
 	if (master->lessor)
-		return idr_find(&master->leases, id) != NULL;
+		return xa_load(&master->leases, id) != NULL;
 	return true;
 }
 
@@ -183,7 +181,7 @@ uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
 /*
  * drm_lease_create - create a new drm_master with leased objects (idr_mutex not held)
  * @lessor: lease holder (or owner) of objects
- * @leases: objects to lease to the new drm_master
+ * @lessee: leaser of objects
  *
  * Uses drm_master_create to allocate a new drm_master, then checks to
  * make sure all of the desired objects can be leased, atomically
@@ -195,35 +193,30 @@ uint32_t drm_lease_filter_crtcs(struct drm_file *file_priv, uint32_t crtcs_in)
  *	ERR_PTR(-EEXIST)	same object specified more than once in the provided list
  *	ERR_PTR(-ENOMEM)	allocation failed
  */
-static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr *leases)
+static struct drm_master *drm_lease_create(struct drm_master *lessor,
+		struct drm_master *lessee)
 {
 	struct drm_device *dev = lessor->dev;
 	int error;
-	struct drm_master *lessee;
-	int object;
 	void *entry;
+	unsigned long index;
 
 	DRM_DEBUG_LEASE("lessor %d\n", lessor->lessee_id);
 
-	lessee = drm_master_create(lessor->dev);
-	if (!lessee) {
-		DRM_DEBUG_LEASE("drm_master_create failed\n");
-		return ERR_PTR(-ENOMEM);
-	}
-
 	mutex_lock(&dev->mode_config.idr_mutex);
 
-	idr_for_each_entry(leases, entry, object) {
+	xa_for_each(&lessee->leases, index, entry) {
 		error = 0;
-		if (!idr_find(&dev->mode_config.crtc_idr, object))
+		if (!xa_load(&dev->mode_config.objects, index))
 			error = -ENOENT;
-		else if (!_drm_lease_held_master(lessor, object))
+		else if (!_drm_lease_held_master(lessor, index))
 			error = -EACCES;
-		else if (_drm_has_leased(lessor, object))
+		else if (_drm_has_leased(lessor, index))
 			error = -EBUSY;
 
 		if (error != 0) {
-			DRM_DEBUG_LEASE("object %d failed %d\n", object, error);
+			DRM_DEBUG_LEASE("object %d failed %d\n", (u32)index,
+					error);
 			goto out_lessee;
 		}
 	}
@@ -236,8 +229,6 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr
 
 	lessee->lessor = drm_master_get(lessor);
 
-	/* Move the leases over */
-	lessee->leases = *leases;
 	DRM_DEBUG_LEASE("new lessee %d %p, lessor %d %p\n", lessee->lessee_id, lessee, lessor->lessee_id, lessor);
 
 	mutex_unlock(&dev->mode_config.idr_mutex);
@@ -246,8 +237,6 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr
 out_lessee:
 	mutex_unlock(&dev->mode_config.idr_mutex);
 
-	drm_master_put(&lessee);
-
 	return ERR_PTR(error);
 }
 
@@ -292,8 +281,6 @@ void drm_lease_destroy(struct drm_master *master)
  */
 static void _drm_lease_revoke(struct drm_master *top)
 {
-	int object;
-	void *entry;
 	struct drm_master *master = top;
 
 	lockdep_assert_held(&top->dev->mode_config.idr_mutex);
@@ -309,8 +296,7 @@ static void _drm_lease_revoke(struct drm_master *top)
 		DRM_DEBUG_LEASE("revoke leases for %p %d\n", master, master->lessee_id);
 
 		/* Evacuate the lease */
-		idr_for_each_entry(&master->leases, entry, object)
-			idr_remove(&master->leases, object);
+		xa_destroy(&master->leases);
 
 		/* Depth-first tree walk */
 		tmp = xa_find(&master->lessees, &index, ULONG_MAX, XA_PRESENT);
@@ -378,11 +364,9 @@ static int validate_lease(struct drm_device *dev,
 	return 0;
 }
 
-static int fill_object_idr(struct drm_device *dev,
-			   struct drm_file *lessor_priv,
-			   struct idr *leases,
-			   int object_count,
-			   u32 *object_ids)
+static int fill_object_array(struct drm_device *dev,
+		struct drm_file *lessor_priv, struct xarray *leases,
+		int object_count, u32 *object_ids)
 {
 	struct drm_mode_object **objects;
 	u32 o;
@@ -431,14 +415,14 @@ static int fill_object_idr(struct drm_device *dev,
 		DRM_DEBUG_LEASE("Adding object %d to lease\n", object_id);
 
 		/*
-		 * We're using an IDR to hold the set of leased
+		 * We're using an array to hold the set of leased
 		 * objects, but we don't need to point at the object's
-		 * data structure from the lease as the main crtc_idr
+		 * data structure from the lease as the main object array
 		 * will be used to actually find that. Instead, all we
 		 * really want is a 'leased/not-leased' result, for
 		 * which any non-NULL pointer will work fine.
 		 */
-		ret = idr_alloc(leases, &drm_lease_idr_object , object_id, object_id + 1, GFP_KERNEL);
+		ret = xa_insert(leases, object_id, xa_mk_value(0), GFP_KERNEL);
 		if (ret < 0) {
 			DRM_DEBUG_LEASE("Object %d cannot be inserted into leases (%d)\n",
 					object_id, ret);
@@ -446,19 +430,21 @@ static int fill_object_idr(struct drm_device *dev,
 		}
 		if (obj->type == DRM_MODE_OBJECT_CRTC && !universal_planes) {
 			struct drm_crtc *crtc = obj_to_crtc(obj);
-			ret = idr_alloc(leases, &drm_lease_idr_object, crtc->primary->base.id, crtc->primary->base.id + 1, GFP_KERNEL);
+			ret = xa_insert(leases, crtc->primary->base.id,
+					xa_mk_value(0), GFP_KERNEL);
 			if (ret < 0) {
 				DRM_DEBUG_LEASE("Object primary plane %d cannot be inserted into leases (%d)\n",
 						object_id, ret);
 				goto out_free_objects;
 			}
-			if (crtc->cursor) {
-				ret = idr_alloc(leases, &drm_lease_idr_object, crtc->cursor->base.id, crtc->cursor->base.id + 1, GFP_KERNEL);
-				if (ret < 0) {
-					DRM_DEBUG_LEASE("Object cursor plane %d cannot be inserted into leases (%d)\n",
-							object_id, ret);
-					goto out_free_objects;
-				}
+			if (!crtc->cursor)
+				continue;
+			ret = xa_insert(leases, crtc->cursor->base.id,
+					xa_mk_value(0), GFP_KERNEL);
+			if (ret < 0) {
+				DRM_DEBUG_LEASE("Object cursor plane %d cannot be inserted into leases (%d)\n",
+						object_id, ret);
+				goto out_free_objects;
 			}
 		}
 	}
@@ -490,9 +476,8 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
 	struct drm_mode_create_lease *cl = data;
 	size_t object_count;
 	int ret = 0;
-	struct idr leases;
 	struct drm_master *lessor = lessor_priv->master;
-	struct drm_master *lessee = NULL;
+	struct drm_master *lessee;
 	struct file *lessee_file = NULL;
 	struct file *lessor_file = lessor_priv->filp;
 	struct drm_file *lessee_priv;
@@ -520,37 +505,42 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
 		return -EINVAL;
 	}
 
-	object_count = cl->object_count;
+	lessee = drm_master_create(lessor->dev);
+	if (!lessee) {
+		DRM_DEBUG_LEASE("drm_master_create failed\n");
+		return -ENOMEM;
+	}
 
-	object_ids = memdup_user(u64_to_user_ptr(cl->object_ids), object_count * sizeof(__u32));
-	if (IS_ERR(object_ids))
-		return PTR_ERR(object_ids);
+	object_count = cl->object_count;
 
-	idr_init(&leases);
+	object_ids = memdup_user(u64_to_user_ptr(cl->object_ids),
+			array_size(object_count, sizeof(__u32)));
+	if (IS_ERR(object_ids)) {
+		ret = PTR_ERR(object_ids);
+		goto out_lessee;
+	}
 
-	/* fill and validate the object idr */
-	ret = fill_object_idr(dev, lessor_priv, &leases,
+	/* fill and validate the object array */
+	ret = fill_object_array(dev, lessor_priv, &lessee->leases,
 			      object_count, object_ids);
 	kfree(object_ids);
 	if (ret) {
 		DRM_DEBUG_LEASE("lease object lookup failed: %i\n", ret);
-		idr_destroy(&leases);
-		return ret;
+		goto out_lessee;
 	}
 
 	/* Allocate a file descriptor for the lease */
-	fd = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
-	if (fd < 0) {
-		idr_destroy(&leases);
-		return fd;
-	}
+	ret = get_unused_fd_flags(cl->flags & (O_CLOEXEC | O_NONBLOCK));
+	if (ret < 0)
+		goto out_lessee;
+	fd = ret;
 
 	DRM_DEBUG_LEASE("Creating lease\n");
-	lessee = drm_lease_create(lessor, &leases);
+	lessee = drm_lease_create(lessor, lessee);
 
 	if (IS_ERR(lessee)) {
 		ret = PTR_ERR(lessee);
-		goto out_leases;
+		goto out_fd;
 	}
 
 	/* Clone the lessor file to create a new file for us */
@@ -558,7 +548,7 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
 	lessee_file = file_clone_open(lessor_file);
 	if (IS_ERR(lessee_file)) {
 		ret = PTR_ERR(lessee_file);
-		goto out_lessee;
+		goto out_fd;
 	}
 
 	lessee_priv = lessee_file->private_data;
@@ -579,13 +569,11 @@ int drm_mode_create_lease_ioctl(struct drm_device *dev,
 	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl succeeded\n");
 	return 0;
 
+out_fd:
+	put_unused_fd(fd);
 out_lessee:
 	drm_master_put(&lessee);
 
-out_leases:
-	put_unused_fd(fd);
-	idr_destroy(&leases);
-
 	DRM_DEBUG_LEASE("drm_mode_create_lease_ioctl failed: %d\n", ret);
 	return ret;
 }
@@ -627,7 +615,7 @@ int drm_mode_list_lessees_ioctl(struct drm_device *dev,
 	count = 0;
 	xa_for_each(&lessor->lessees, index, lessee) {
 		/* Only list un-revoked leases */
-		if (!idr_is_empty(&lessee->leases)) {
+		if (!xa_empty(&lessee->leases)) {
 			if (count_lessees > count) {
 				DRM_DEBUG_LEASE("Add lessee %d\n", lessee->lessee_id);
 				ret = put_user(lessee->lessee_id, lessee_ids + count);
@@ -663,10 +651,10 @@ int drm_mode_get_lease_ioctl(struct drm_device *dev,
 	__u32 __user *object_ids = (__u32 __user *) (uintptr_t) (arg->objects_ptr);
 	__u32 count_objects = arg->count_objects;
 	struct drm_master *lessee = lessee_priv->master;
-	struct idr *object_idr;
+	struct xarray *objects;
 	int count;
 	void *entry;
-	int object;
+	unsigned long index;
 	int ret = 0;
 
 	if (arg->pad)
@@ -682,16 +670,16 @@ int drm_mode_get_lease_ioctl(struct drm_device *dev,
 
 	if (lessee->lessor == NULL)
 		/* owner can use all objects */
-		object_idr = &lessee->dev->mode_config.crtc_idr;
+		objects = &lessee->dev->mode_config.objects;
 	else
-		/* lessee can only use allowed object */
-		object_idr = &lessee->leases;
+		/* lessee can only use allowed objects */
+		objects = &lessee->leases;
 
 	count = 0;
-	idr_for_each_entry(object_idr, entry, object) {
+	xa_for_each(objects, index, entry) {
 		if (count_objects > count) {
-			DRM_DEBUG_LEASE("adding object %d\n", object);
-			ret = put_user(object, object_ids + count);
+			DRM_DEBUG_LEASE("adding object %d\n", (u32)index);
+			ret = put_user((u32)index, object_ids + count);
 			if (ret)
 				break;
 		}
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 609b30d7dcb1..10c616e0f591 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -393,7 +393,7 @@ void drm_mode_config_init(struct drm_device *dev)
 	INIT_LIST_HEAD(&dev->mode_config.property_list);
 	INIT_LIST_HEAD(&dev->mode_config.property_blob_list);
 	INIT_LIST_HEAD(&dev->mode_config.plane_list);
-	idr_init(&dev->mode_config.crtc_idr);
+	xa_init_flags(&dev->mode_config.objects, XA_FLAGS_ALLOC1);
 	xa_init_flags(&dev->mode_config.tiles, XA_FLAGS_ALLOC1);
 	ida_init(&dev->mode_config.connector_ida);
 	spin_lock_init(&dev->mode_config.connector_list_lock);
@@ -495,7 +495,6 @@ void drm_mode_config_cleanup(struct drm_device *dev)
 	}
 
 	ida_destroy(&dev->mode_config.connector_ida);
-	idr_destroy(&dev->mode_config.crtc_idr);
 	drm_modeset_lock_fini(&dev->mode_config.connection_mutex);
 }
 EXPORT_SYMBOL(drm_mode_config_cleanup);
diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c
index 004191d01772..686fba472abf 100644
--- a/drivers/gpu/drm/drm_mode_object.c
+++ b/drivers/gpu/drm/drm_mode_object.c
@@ -37,24 +37,23 @@ int __drm_mode_object_add(struct drm_device *dev, struct drm_mode_object *obj,
 {
 	int ret;
 
-	mutex_lock(&dev->mode_config.idr_mutex);
-	ret = idr_alloc(&dev->mode_config.crtc_idr, register_obj ? obj : NULL,
-			1, 0, GFP_KERNEL);
-	if (ret >= 0) {
-		/*
-		 * Set up the object linking under the protection of the idr
-		 * lock so that other users can't see inconsistent state.
-		 */
-		obj->id = ret;
-		obj->type = obj_type;
-		if (obj_free_cb) {
-			obj->free_cb = obj_free_cb;
-			kref_init(&obj->refcount);
-		}
+	/*
+	 * Initialise the object before putting the object in the array
+	 * so that other users can't see inconsistent state.  The ID is
+	 * initialised before the object is inserted into the array with
+	 * a write barrier so even RCU-protected walkers can't see an
+	 * uninitialised ID.
+	 */
+	obj->type = obj_type;
+	if (obj_free_cb) {
+		obj->free_cb = obj_free_cb;
+		kref_init(&obj->refcount);
 	}
-	mutex_unlock(&dev->mode_config.idr_mutex);
 
-	return ret < 0 ? ret : 0;
+	ret = xa_alloc(&dev->mode_config.objects, &obj->id,
+			register_obj ? obj : NULL, xa_limit_31b, GFP_KERNEL);
+
+	return ret;
 }
 
 /**
@@ -78,9 +77,7 @@ int drm_mode_object_add(struct drm_device *dev,
 void drm_mode_object_register(struct drm_device *dev,
 			      struct drm_mode_object *obj)
 {
-	mutex_lock(&dev->mode_config.idr_mutex);
-	idr_replace(&dev->mode_config.crtc_idr, obj, obj->id);
-	mutex_unlock(&dev->mode_config.idr_mutex);
+	xa_store(&dev->mode_config.objects, obj->id, obj, 0);
 }
 
 /**
@@ -97,12 +94,10 @@ void drm_mode_object_register(struct drm_device *dev,
 void drm_mode_object_unregister(struct drm_device *dev,
 				struct drm_mode_object *object)
 {
-	mutex_lock(&dev->mode_config.idr_mutex);
 	if (object->id) {
-		idr_remove(&dev->mode_config.crtc_idr, object->id);
+		xa_erase(&dev->mode_config.objects, object->id);
 		object->id = 0;
 	}
-	mutex_unlock(&dev->mode_config.idr_mutex);
 }
 
 /**
@@ -128,10 +123,10 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev,
 					       struct drm_file *file_priv,
 					       uint32_t id, uint32_t type)
 {
-	struct drm_mode_object *obj = NULL;
+	struct drm_mode_object *obj;
 
-	mutex_lock(&dev->mode_config.idr_mutex);
-	obj = idr_find(&dev->mode_config.crtc_idr, id);
+	xa_lock(&dev->mode_config.objects);
+	obj = xa_load(&dev->mode_config.objects, id);
 	if (obj && type != DRM_MODE_OBJECT_ANY && obj->type != type)
 		obj = NULL;
 	if (obj && obj->id != id)
@@ -145,7 +140,7 @@ struct drm_mode_object *__drm_mode_object_find(struct drm_device *dev,
 		if (!kref_get_unless_zero(&obj->refcount))
 			obj = NULL;
 	}
-	mutex_unlock(&dev->mode_config.idr_mutex);
+	xa_unlock(&dev->mode_config.objects);
 
 	return obj;
 }
diff --git a/include/drm/drm_auth.h b/include/drm/drm_auth.h
index fbb58264538b..88c8bbf14916 100644
--- a/include/drm/drm_auth.h
+++ b/include/drm/drm_auth.h
@@ -90,7 +90,7 @@ struct drm_master {
 
 	struct drm_master *lessor;
 	int	lessee_id;
-	struct idr leases;
+	struct xarray leases;
 	struct xarray lessees;
 };
 
diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index fea334d99201..64bdf66d878c 100644
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -397,12 +397,12 @@ struct drm_mode_config {
 	struct mutex idr_mutex;
 
 	/**
-	 * @crtc_idr:
+	 * @objects:
 	 *
-	 * Main KMS ID tracking object. Use this idr for all IDs, fb, crtc,
+	 * Main KMS ID tracking object. Use this array for all IDs, fb, crtc,
 	 * connector, modes - just makes life easier to have only one.
 	 */
-	struct idr crtc_idr;
+	struct xarray objects;
 
 	/**
 	 * @tiles:
-- 
2.20.1



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