[PATCH 27/34] drm/qxl: Convert surf_id_idr to XArray

[Matthew Wilcox]

Signed-off-by: Matthew Wilcox <willy at infradead.org>
---
 drivers/gpu/drm/qxl/qxl_cmd.c | 60 ++++++++++++-----------------------
 drivers/gpu/drm/qxl/qxl_drv.h |  3 +-
 drivers/gpu/drm/qxl/qxl_kms.c |  5 +--
 3 files changed, 23 insertions(+), 45 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_cmd.c b/drivers/gpu/drm/qxl/qxl_cmd.c
index dffc5093ff16..afe8079453af 100644
--- a/drivers/gpu/drm/qxl/qxl_cmd.c
+++ b/drivers/gpu/drm/qxl/qxl_cmd.c
@@ -420,41 +420,27 @@ void qxl_io_monitors_config(struct qxl_device *qdev)
 int qxl_surface_id_alloc(struct qxl_device *qdev,
 		      struct qxl_bo *surf)
 {
-	uint32_t handle;
-	int idr_ret;
-	int count = 0;
+	int ret;
 again:
-	idr_preload(GFP_ATOMIC);
-	spin_lock(&qdev->surf_id_idr_lock);
-	idr_ret = idr_alloc(&qdev->surf_id_idr, NULL, 1, 0, GFP_NOWAIT);
-	spin_unlock(&qdev->surf_id_idr_lock);
-	idr_preload_end();
-	if (idr_ret < 0)
-		return idr_ret;
-	handle = idr_ret;
-
-	if (handle >= qdev->rom->n_surfaces) {
-		count++;
-		spin_lock(&qdev->surf_id_idr_lock);
-		idr_remove(&qdev->surf_id_idr, handle);
-		spin_unlock(&qdev->surf_id_idr_lock);
+	ret = xa_alloc(&qdev->surfaces, &surf->surface_id, NULL,
+			XA_LIMIT(0, qdev->rom->n_surfaces - 1), GFP_ATOMIC);
+	if (ret == -EBUSY) {
 		qxl_reap_surface_id(qdev, 2);
 		goto again;
 	}
-	surf->surface_id = handle;
+	if (ret < 0)
+		return ret;
 
-	spin_lock(&qdev->surf_id_idr_lock);
-	qdev->last_alloced_surf_id = handle;
-	spin_unlock(&qdev->surf_id_idr_lock);
+	xa_lock(&qdev->surfaces);
+	qdev->last_alloced_surf_id = surf->surface_id;
+	xa_unlock(&qdev->surfaces);
 	return 0;
 }
 
 void qxl_surface_id_dealloc(struct qxl_device *qdev,
 			    uint32_t surface_id)
 {
-	spin_lock(&qdev->surf_id_idr_lock);
-	idr_remove(&qdev->surf_id_idr, surface_id);
-	spin_unlock(&qdev->surf_id_idr_lock);
+	xa_erase(&qdev->surfaces, surface_id);
 }
 
 int qxl_hw_surface_alloc(struct qxl_device *qdev,
@@ -507,9 +493,7 @@ int qxl_hw_surface_alloc(struct qxl_device *qdev,
 	qxl_release_fence_buffer_objects(release);
 
 	surf->hw_surf_alloc = true;
-	spin_lock(&qdev->surf_id_idr_lock);
-	idr_replace(&qdev->surf_id_idr, surf, surf->surface_id);
-	spin_unlock(&qdev->surf_id_idr_lock);
+	xa_store(&qdev->surfaces, surf->surface_id, surf, GFP_KERNEL);
 	return 0;
 }
 
@@ -531,10 +515,8 @@ int qxl_hw_surface_dealloc(struct qxl_device *qdev,
 		return ret;
 
 	surf->surf_create = NULL;
-	/* remove the surface from the idr, but not the surface id yet */
-	spin_lock(&qdev->surf_id_idr_lock);
-	idr_replace(&qdev->surf_id_idr, NULL, surf->surface_id);
-	spin_unlock(&qdev->surf_id_idr_lock);
+	/* remove the surface from the array, but don't free the surface id */
+	xa_store(&qdev->surfaces, surf->surface_id, NULL, 0);
 	surf->hw_surf_alloc = false;
 
 	id = surf->surface_id;
@@ -623,20 +605,20 @@ static int qxl_reap_surface_id(struct qxl_device *qdev, int max_to_reap)
 	mutex_lock(&qdev->surf_evict_mutex);
 again:
 
-	spin_lock(&qdev->surf_id_idr_lock);
+	xa_lock(&qdev->surfaces);
 	start = qdev->last_alloced_surf_id + 1;
-	spin_unlock(&qdev->surf_id_idr_lock);
+	xa_unlock(&qdev->surfaces);
 
 	for (i = start; i < start + qdev->rom->n_surfaces; i++) {
 		void *objptr;
 		int surfid = i % qdev->rom->n_surfaces;
 
-		/* this avoids the case where the objects is in the
-		   idr but has been evicted half way - its makes
-		   the idr lookup atomic with the eviction */
-		spin_lock(&qdev->surf_id_idr_lock);
-		objptr = idr_find(&qdev->surf_id_idr, surfid);
-		spin_unlock(&qdev->surf_id_idr_lock);
+		/* this avoids the case where the object is in the
+		   array but has been evicted half way - it makes
+		   the array lookup atomic with the eviction */
+		xa_lock(&qdev->surfaces);
+		objptr = xa_load(&qdev->surfaces, surfid);
+		xa_unlock(&qdev->surfaces);
 
 		if (!objptr)
 			continue;
diff --git a/drivers/gpu/drm/qxl/qxl_drv.h b/drivers/gpu/drm/qxl/qxl_drv.h
index 3abd432a4b85..8d0254a133dc 100644
--- a/drivers/gpu/drm/qxl/qxl_drv.h
+++ b/drivers/gpu/drm/qxl/qxl_drv.h
@@ -260,8 +260,7 @@ struct qxl_device {
 
 	struct mutex		update_area_mutex;
 
-	struct idr	surf_id_idr;
-	spinlock_t surf_id_idr_lock;
+	struct xarray	surfaces;
 	int last_alloced_surf_id;
 
 	struct mutex surf_evict_mutex;
diff --git a/drivers/gpu/drm/qxl/qxl_kms.c b/drivers/gpu/drm/qxl/qxl_kms.c
index b2cc71c95142..dafdb61f7a32 100644
--- a/drivers/gpu/drm/qxl/qxl_kms.c
+++ b/drivers/gpu/drm/qxl/qxl_kms.c
@@ -249,10 +249,7 @@ int qxl_device_init(struct qxl_device *qdev,
 
 	xa_init_flags(&qdev->releases, XA_FLAGS_ALLOC1);
 	spin_lock_init(&qdev->release_lock);
-
-	idr_init(&qdev->surf_id_idr);
-	spin_lock_init(&qdev->surf_id_idr_lock);
-
+	xa_init_flags(&qdev->surfaces, XA_FLAGS_ALLOC1);
 	mutex_init(&qdev->async_io_mutex);
 
 	/* reset the device into a known state - no memslots, no primary
-- 
2.20.1