drm: Use XArray instead of IDR for minors

From Michal Winiarski
d2e3d344e20e605378556610811549249298d0aa in linux-6.6.y/6.6.53
5fbca8b48b3050ae7fb611a8b09af60012ed6de1 in mainline linux

diff --git a/sys/dev/pci/drm/drm_drv.c b/sys/dev/pci/drm/drm_drv.c
index 7db7ae1..7dbc555 100644 (file)
--- a/sys/dev/pci/drm/drm_drv.c
+++ b/sys/dev/pci/drm/drm_drv.c
@@ -47,6 +47,7 @@
 #include <linux/pseudo_fs.h>
 #include <linux/slab.h>
 #include <linux/srcu.h>
+#include <linux/xarray.h>
 #include <linux/suspend.h>
 
 #include <drm/drm_accel.h>
@@ -70,8 +71,7 @@ MODULE_AUTHOR("Gareth Hughes, Leif Delgass, José Fonseca, Jon Smirl");
 MODULE_DESCRIPTION("DRM shared core routines");
 MODULE_LICENSE("GPL and additional rights");
 
-static DEFINE_SPINLOCK(drm_minor_lock);
-static struct idr drm_minors_idr;
+static DEFINE_XARRAY_ALLOC(drm_minors_xa);
 
 /*
  * If the drm core fails to init for whatever reason,
@@ -162,7 +162,6 @@ static struct drm_minor **drm_minor_get_slot(struct drm_device *dev,
 static void drm_minor_alloc_release(struct drm_device *dev, void *data)
 {
        struct drm_minor *minor = data;
-       unsigned long flags;
 
        WARN_ON(dev != minor->dev);
 
@@ -170,20 +169,18 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data)
        put_device(minor->kdev);
 #endif
 
-       if (minor->type == DRM_MINOR_ACCEL) {
+       if (minor->type == DRM_MINOR_ACCEL)
                accel_minor_remove(minor->index);
-       } else {
-               spin_lock_irqsave(&drm_minor_lock, flags);
-               idr_remove(&drm_minors_idr, minor->index);
-               spin_unlock_irqrestore(&drm_minor_lock, flags);
-       }
+       else
+               xa_erase(&drm_minors_xa, minor->index);
 }
 
+#define DRM_MINOR_LIMIT(t) ({ typeof(t) _t = (t); XA_LIMIT(64 * _t, 64 * _t + 63); })
+
 static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
 {
        struct drm_minor *minor;
-       unsigned long flags;
-       int r;
+       int index, r;
 
        minor = drmm_kzalloc(dev, sizeof(*minor), GFP_KERNEL);
        if (!minor)
@@ -192,24 +189,17 @@ static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
        minor->type = type;
        minor->dev = dev;
 
-       idr_preload(GFP_KERNEL);
        if (type == DRM_MINOR_ACCEL) {
                r = accel_minor_alloc();
+               index = r;
        } else {
-               spin_lock_irqsave(&drm_minor_lock, flags);
-               r = idr_alloc(&drm_minors_idr,
-                       NULL,
-                       64 * type,
-                       64 * (type + 1),
-                       GFP_NOWAIT);
-               spin_unlock_irqrestore(&drm_minor_lock, flags);
+               r = xa_alloc(&drm_minors_xa, &index, NULL, DRM_MINOR_LIMIT(type), GFP_KERNEL);
        }
-       idr_preload_end();
 
        if (r < 0)
                return r;
 
-       minor->index = r;
+       minor->index = index;
 
        r = drmm_add_action_or_reset(dev, drm_minor_alloc_release, minor);
        if (r)
@@ -228,10 +218,8 @@ static int drm_minor_alloc(struct drm_device *dev, enum drm_minor_type type)
 static int drm_minor_register(struct drm_device *dev, enum drm_minor_type type)
 {
        struct drm_minor *minor;
-       unsigned long flags;
-#ifdef __linux__
+       void *entry;
        int ret;
-#endif
 
        DRM_DEBUG("\n");
 
@@ -261,25 +249,27 @@ static int drm_minor_register(struct drm_device *dev, enum drm_minor_type type)
        if (minor->type == DRM_MINOR_ACCEL) {
                accel_minor_replace(minor, minor->index);
        } else {
-               spin_lock_irqsave(&drm_minor_lock, flags);
-               idr_replace(&drm_minors_idr, minor, minor->index);
-               spin_unlock_irqrestore(&drm_minor_lock, flags);
+               entry = xa_store(&drm_minors_xa, minor->index, minor, GFP_KERNEL);
+               if (xa_is_err(entry)) {
+                       ret = xa_err(entry);
+                       goto err_debugfs;
+               }
+               WARN_ON(entry);
        }
 
        DRM_DEBUG("new minor registered %d\n", minor->index);
        return 0;
 
-#ifdef __linux__
 err_debugfs:
+#ifdef __linux__
        drm_debugfs_cleanup(minor);
-       return ret;
 #endif
+       return ret;
 }
 
 static void drm_minor_unregister(struct drm_device *dev, enum drm_minor_type type)
 {
        struct drm_minor *minor;
-       unsigned long flags;
 
        minor = *drm_minor_get_slot(dev, type);
 #ifdef __linux__
@@ -290,13 +280,10 @@ static void drm_minor_unregister(struct drm_device *dev, enum drm_minor_type typ
                return;
 
        /* replace @minor with NULL so lookups will fail from now on */
-       if (minor->type == DRM_MINOR_ACCEL) {
+       if (minor->type == DRM_MINOR_ACCEL)
                accel_minor_replace(NULL, minor->index);
-       } else {
-               spin_lock_irqsave(&drm_minor_lock, flags);
-               idr_replace(&drm_minors_idr, NULL, minor->index);
-               spin_unlock_irqrestore(&drm_minor_lock, flags);
-       }
+       else
+               xa_store(&drm_minors_xa, minor->index, NULL, GFP_KERNEL);
 
 #ifdef __linux__
        device_del(minor->kdev);
@@ -317,13 +304,12 @@ static void drm_minor_unregister(struct drm_device *dev, enum drm_minor_type typ
 struct drm_minor *drm_minor_acquire(unsigned int minor_id)
 {
        struct drm_minor *minor;
-       unsigned long flags;
 
-       spin_lock_irqsave(&drm_minor_lock, flags);
-       minor = idr_find(&drm_minors_idr, minor_id);
+       xa_lock(&drm_minors_xa);
+       minor = xa_load(&drm_minors_xa, minor_id);
        if (minor)
                drm_dev_get(minor->dev);
-       spin_unlock_irqrestore(&drm_minor_lock, flags);
+       xa_unlock(&drm_minors_xa);
 
        if (!minor) {
                return ERR_PTR(-ENODEV);
@@ -1180,7 +1166,7 @@ static void drm_core_exit(void)
        debugfs_remove(drm_debugfs_root);
        drm_sysfs_destroy();
 #endif
-       idr_destroy(&drm_minors_idr);
+       WARN_ON(!xa_empty(&drm_minors_xa));
        drm_connector_ida_destroy();
 }
 
@@ -1191,7 +1177,6 @@ static int __init drm_core_init(void)
 #endif
 
        drm_connector_ida_init();
-       idr_init(&drm_minors_idr);
        drm_memcpy_init_early();
 
 #ifdef __linux__