linux-kernel - [PATCH v2 3/6] drm: Convert syncobj

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Message-ID: <20250821145429.305526-4-sidhartha.kumar@oracle.com>
Date: Thu, 21 Aug 2025 14:54:26 +0000
From: Sidhartha Kumar <sidhartha.kumar@...cle.com>
To: linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Cc: maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
        airlied@...il.com, simona@...ll.ch, willy@...radead.org,
        sidhartha.kumar@...cle.com
Subject: [PATCH v2 3/6] drm: Convert syncobj_idr to XArray

From: Matthew Wilcox <willy@...radead.org>

Remove syncobj_table_lock by converting the syncobj_idr to an XArray.

Signed-off-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
---
 drivers/gpu/drm/drm_syncobj.c | 64 +++++++++++------------------------
 include/drm/drm_file.h        |  6 ++--
 2 files changed, 22 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index e1b0fa4000cd..091f43cf11ba 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -250,14 +250,12 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 {
 	struct drm_syncobj *syncobj;
 
-	spin_lock(&file_private->syncobj_table_lock);
-
-	/* Check if we currently have a reference on the object */
-	syncobj = idr_find(&file_private->syncobj_idr, handle);
+	/* Get a reference on the object */
+	xa_lock(&file_private->syncobjs);
+	syncobj = xa_load(&file_private->syncobjs, handle);
 	if (syncobj)
 		drm_syncobj_get(syncobj);
-
-	spin_unlock(&file_private->syncobj_table_lock);
+	xa_unlock(&file_private->syncobjs);
 
 	return syncobj;
 }
@@ -598,23 +596,16 @@ int drm_syncobj_get_handle(struct drm_file *file_private,
 {
 	int ret;
 
-	/* take a reference to put in the idr */
+	/* take a reference to put in the XArray */
 	drm_syncobj_get(syncobj);
 
-	idr_preload(GFP_KERNEL);
-	spin_lock(&file_private->syncobj_table_lock);
-	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
-	spin_unlock(&file_private->syncobj_table_lock);
+	ret = xa_alloc(&file_private->syncobjs, handle, syncobj, xa_limit_31b,
+			GFP_KERNEL);
 
-	idr_preload_end();
-
-	if (ret < 0) {
+	if (ret < 0)
 		drm_syncobj_put(syncobj);
-		return ret;
-	}
 
-	*handle = ret;
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(drm_syncobj_get_handle);
 
@@ -638,9 +629,7 @@ static int drm_syncobj_destroy(struct drm_file *file_private,
 {
 	struct drm_syncobj *syncobj;
 
-	spin_lock(&file_private->syncobj_table_lock);
-	syncobj = idr_remove(&file_private->syncobj_idr, handle);
-	spin_unlock(&file_private->syncobj_table_lock);
+	syncobj = xa_erase(&file_private->syncobjs, handle);
 
 	if (!syncobj)
 		return -EINVAL;
@@ -726,16 +715,10 @@ static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
 	syncobj = fd_file(f)->private_data;
 	drm_syncobj_get(syncobj);
 
-	idr_preload(GFP_KERNEL);
-	spin_lock(&file_private->syncobj_table_lock);
-	ret = idr_alloc(&file_private->syncobj_idr, syncobj, 1, 0, GFP_NOWAIT);
-	spin_unlock(&file_private->syncobj_table_lock);
-	idr_preload_end();
+	ret = xa_alloc(&file_private->syncobjs, handle, syncobj, xa_limit_31b,
+			GFP_KERNEL);
 
-	if (ret > 0) {
-		*handle = ret;
-		ret = 0;
-	} else
+	if (ret < 0)
 		drm_syncobj_put(syncobj);
 
 	return ret;
@@ -814,17 +797,7 @@ static int drm_syncobj_export_sync_file(struct drm_file *file_private,
 void
 drm_syncobj_open(struct drm_file *file_private)
 {
-	idr_init_base(&file_private->syncobj_idr, 1);
-	spin_lock_init(&file_private->syncobj_table_lock);
-}
-
-static int
-drm_syncobj_release_handle(int id, void *ptr, void *data)
-{
-	struct drm_syncobj *syncobj = ptr;
-
-	drm_syncobj_put(syncobj);
-	return 0;
+	xa_init_flags(&file_private->syncobjs, XA_FLAGS_ALLOC1);
 }
 
 /**
@@ -838,9 +811,12 @@ drm_syncobj_release_handle(int id, void *ptr, void *data)
 void
 drm_syncobj_release(struct drm_file *file_private)
 {
-	idr_for_each(&file_private->syncobj_idr,
-		     &drm_syncobj_release_handle, file_private);
-	idr_destroy(&file_private->syncobj_idr);
+	struct drm_syncobj *syncobj;
+	unsigned long index;
+
+	xa_for_each(&file_private->syncobjs, index, syncobj)
+		drm_syncobj_put(syncobj);
+	xa_destroy(&file_private->syncobjs);
 }
 
 int
diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
index 115763799625..ee5a16338c86 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -309,10 +309,8 @@ struct drm_file {
 	/** @table_lock: Protects @object_idr. */
 	spinlock_t table_lock;
 
-	/** @syncobj_idr: Mapping of sync object handles to object pointers. */
-	struct idr syncobj_idr;
-	/** @syncobj_table_lock: Protects @syncobj_idr. */
-	spinlock_t syncobj_table_lock;
+	/** @syncobjs: Mapping of sync object handles to object pointers. */
+	struct xarray syncobjs;
 
 	/** @filp: Pointer to the core file structure. */
 	struct file *filp;
-- 
2.43.0