[PATCH 1/2] drm/syncobj: Convert syncobj_idr to XArray

[Chris Wilson]

Prior to making the syncobj lookup lockless, update the idr to the new
XArray API.

Based on a patch by Matthew Wilcox <willy at infradead.org>
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/drm_syncobj.c | 64 ++++++++++-------------------------
 include/drm/drm_file.h        |  7 ++--
 2 files changed, 21 insertions(+), 50 deletions(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 1438dcb3ebb1..4fc71dc9fc43 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -86,14 +86,13 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private,
 {
 	struct drm_syncobj *syncobj;
 
-	spin_lock(&file_private->syncobj_table_lock);
+	xa_lock(&file_private->syncobjs);
 
-	/* Check if we currently have a reference on the object */
-	syncobj = idr_find(&file_private->syncobj_idr, handle);
+	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;
 }
@@ -366,23 +365,14 @@ int drm_syncobj_get_handle(struct drm_file *file_private,
 {
 	int ret;
 
-	/* take a reference to put in the idr */
 	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();
-
-	if (ret < 0) {
+	ret = xa_alloc(&file_private->syncobjs, handle, syncobj,
+		       xa_limit_32b, GFP_KERNEL);
+	if (ret < 0)
 		drm_syncobj_put(syncobj);
-		return ret;
-	}
 
-	*handle = ret;
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(drm_syncobj_get_handle);
 
@@ -406,10 +396,7 @@ 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;
 
@@ -492,20 +479,12 @@ static int drm_syncobj_fd_to_handle(struct drm_file *file_private,
 		return -EINVAL;
 	}
 
-	/* take a reference to put in the idr */
 	syncobj = f.file->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();
-
-	if (ret > 0) {
-		*handle = ret;
-		ret = 0;
-	} else
+	ret = xa_alloc(&file_private->syncobjs, handle, syncobj,
+		       xa_limit_32b, GFP_KERNEL);
+	if (ret < 0)
 		drm_syncobj_put(syncobj);
 
 	fdput(f);
@@ -575,17 +554,7 @@ 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);
 }
 
 /**
@@ -599,9 +568,12 @@ 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 67af60bb527a..c6efb5f83fcf 100644
--- a/include/drm/drm_file.h
+++ b/include/drm/drm_file.h
@@ -33,6 +33,7 @@
 #include <linux/types.h>
 #include <linux/completion.h>
 #include <linux/idr.h>
+#include <linux/xarray.h>
 
 #include <uapi/drm/drm.h>
 
@@ -251,10 +252,8 @@ 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;
-- 
2.23.0.rc0