[PATCH 1/6] drm: Convert aux_idr to XArray

[Sidhartha Kumar]

From: Matthew Wilcox <wi...@infradead.org>

Remove aux_idr_mutex by converting aux_idr to an XArray.

Signed-off-by: Matthew Wilcox <wi...@infradead.org>
Signed-off-by: Sidhartha Kumar <sidhartha.ku...@oracle.com>
---
 drivers/gpu/drm/display/drm_dp_aux_dev.c | 38 ++++++++++--------------
 1 file changed, 15 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_aux_dev.c 
b/drivers/gpu/drm/display/drm_dp_aux_dev.c
index 29555b9f03c8..edecfea44da8 100644
--- a/drivers/gpu/drm/display/drm_dp_aux_dev.c
+++ b/drivers/gpu/drm/display/drm_dp_aux_dev.c
@@ -52,8 +52,7 @@ 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 struct class *drm_dp_aux_dev_class;
 static int drm_dev_major = -1;
 
@@ -61,11 +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 (aux_dev && !kref_get_unless_zero(&aux_dev->refcount))
                aux_dev = NULL;
-       mutex_unlock(&aux_idr_mutex);
+       xa_unlock(&aux_xa);
 
        return aux_dev;
 }
@@ -73,7 +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)
@@ -82,14 +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(&aux_idr, aux_dev, 0, DRM_AUX_MINORS, GFP_KERNEL);
-       mutex_unlock(&aux_idr_mutex);
-       if (index < 0) {
+       err = xa_alloc(&aux_xa, &aux_dev->index,
+                               XA_LIMIT(0, DRM_AUX_MINORS - 1), aux_dev, 
GFP_KERNEL);
+       if (err < 0) {
                kfree(aux_dev);
-               return ERR_PTR(index);
+               return ERR_PTR(err);
        }
-       aux_dev->index = index;
 
        return aux_dev;
 }
@@ -250,22 +247,19 @@ 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;
 }
 
@@ -284,9 +278,7 @@ void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
         */
        aux->drm_dev = NULL;
 
-       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));
-- 
2.43.0