From: Matthew Wilcox <willy@infradead.org>
Date: Tue, 8 Jan 2019 14:15:14 +0000 (-0500)
Subject: drm: Convert aux_idr to XArray
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=18ba7d8f9c8c531865e18ed13fc073261cc3cd7f;p=users%2Fwilly%2Fxarray.git

drm: Convert aux_idr to XArray

Signed-off-by: Matthew Wilcox <willy@infradead.org>
---

diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
index 5be28e3295f3..aecd5e75b476 100644
--- a/drivers/gpu/drm/drm_dp_aux_dev.c
+++ b/drivers/gpu/drm/drm_dp_aux_dev.c
@@ -51,8 +51,8 @@ struct drm_dp_aux_dev {
 
 #define DRM_AUX_MINORS	256
 #define AUX_MAX_OFFSET	(1 << 20)
-static DEFINE_IDR(aux_idr);
-static DEFINE_MUTEX(aux_idr_mutex);
+static DEFINE_XARRAY_ALLOC(aux_xa);
+static u32 aux_xa_next;
 static struct class *drm_dp_aux_dev_class;
 static int drm_dev_major = -1;
 
@@ -60,11 +60,11 @@ static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
 {
 	struct drm_dp_aux_dev *aux_dev = NULL;
 
-	mutex_lock(&aux_idr_mutex);
-	aux_dev = idr_find(&aux_idr, index);
+	xa_lock(&aux_xa);
+	aux_dev = xa_load(&aux_xa, index);
 	if (!kref_get_unless_zero(&aux_dev->refcount))
 		aux_dev = NULL;
-	mutex_unlock(&aux_idr_mutex);
+	xa_unlock(&aux_xa);
 
 	return aux_dev;
 }
@@ -72,7 +72,7 @@ static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_minor(unsigned index)
 static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
 {
 	struct drm_dp_aux_dev *aux_dev;
-	int index;
+	int err;
 
 	aux_dev = kzalloc(sizeof(*aux_dev), GFP_KERNEL);
 	if (!aux_dev)
@@ -81,15 +81,12 @@ static struct drm_dp_aux_dev *alloc_drm_dp_aux_dev(struct drm_dp_aux *aux)
 	atomic_set(&aux_dev->usecount, 1);
 	kref_init(&aux_dev->refcount);
 
-	mutex_lock(&aux_idr_mutex);
-	index = idr_alloc_cyclic(&aux_idr, aux_dev, 0, DRM_AUX_MINORS,
-				 GFP_KERNEL);
-	mutex_unlock(&aux_idr_mutex);
-	if (index < 0) {
+	err = xa_alloc_cyclic(&aux_xa, &aux_dev->index, aux_dev,
+			XA_LIMIT(0, DRM_AUX_MINORS), &aux_xa_next, GFP_KERNEL);
+	if (err < 0) {
 		kfree(aux_dev);
-		return ERR_PTR(index);
+		return ERR_PTR(err);
 	}
-	aux_dev->index = index;
 
 	return aux_dev;
 }
@@ -248,22 +245,19 @@ static const struct file_operations auxdev_fops = {
 
 static struct drm_dp_aux_dev *drm_dp_aux_dev_get_by_aux(struct drm_dp_aux *aux)
 {
-	struct drm_dp_aux_dev *iter, *aux_dev = NULL;
-	int id;
+	struct drm_dp_aux_dev *aux_dev;
+	unsigned long id;
 
 	/* don't increase kref count here because this function should only be
 	 * used by drm_dp_aux_unregister_devnode. Thus, it will always have at
 	 * least one reference - the one that drm_dp_aux_register_devnode
 	 * created
 	 */
-	mutex_lock(&aux_idr_mutex);
-	idr_for_each_entry(&aux_idr, iter, id) {
-		if (iter->aux == aux) {
-			aux_dev = iter;
+	xa_for_each(&aux_xa, id, aux_dev) {
+		if (aux_dev->aux == aux)
 			break;
-		}
 	}
-	mutex_unlock(&aux_idr_mutex);
+
 	return aux_dev;
 }
 
@@ -276,9 +270,7 @@ void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
 	if (!aux_dev) /* attach must have failed */
 		return;
 
-	mutex_lock(&aux_idr_mutex);
-	idr_remove(&aux_idr, aux_dev->index);
-	mutex_unlock(&aux_idr_mutex);
+	xa_erase(&aux_xa, aux_dev->index);
 
 	atomic_dec(&aux_dev->usecount);
 	wait_var_event(&aux_dev->usecount, !atomic_read(&aux_dev->usecount));