This is a note to let you know that I've just added the patch titled
drm: Use XArray instead of IDR for minors
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-use-xarray-instead-of-idr-for-minors.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 09e7b5460a3bf1ee920c606281a940fdfac46bad
Author: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Date: Fri Aug 23 18:30:46 2024 +0200
drm: Use XArray instead of IDR for minors
[ Upstream commit 5fbca8b48b3050ae7fb611a8b09af60012ed6de1 ]
IDR is deprecated, and since XArray manages its own state with internal
locking, it simplifies the locking on DRM side.
Additionally, don't use the IRQ-safe variant, since operating on drm
minor is not done in IRQ context.
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Acked-by: James Zhu <James.Zhu@xxxxxxx>
Acked-by: Christian König <christian.koenig@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240823163048.2676257-2-michal.winiarski@xxxxxxxxx
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 71bb8806dc5f5..54b0832a8b600 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -34,6 +34,7 @@
#include <linux/pseudo_fs.h>
#include <linux/slab.h>
#include <linux/srcu.h>
+#include <linux/xarray.h>
#include <drm/drm_accel.h>
#include <drm/drm_cache.h>
@@ -54,8 +55,7 @@ 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,
@@ -101,26 +101,23 @@ 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);
put_device(minor->kdev);
- 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)
@@ -129,24 +126,17 @@ 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)
@@ -163,7 +153,7 @@ 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;
+ void *entry;
int ret;
DRM_DEBUG("\n");
@@ -190,9 +180,12 @@ 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);
@@ -206,20 +199,16 @@ static int drm_minor_register(struct drm_device *dev, enum drm_minor_type type)
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);
if (!minor || !device_is_registered(minor->kdev))
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);
device_del(minor->kdev);
dev_set_drvdata(minor->kdev, NULL); /* safety belt */
@@ -238,13 +227,12 @@ 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);
@@ -1073,7 +1061,7 @@ static void drm_core_exit(void)
unregister_chrdev(DRM_MAJOR, "drm");
debugfs_remove(drm_debugfs_root);
drm_sysfs_destroy();
- idr_destroy(&drm_minors_idr);
+ WARN_ON(!xa_empty(&drm_minors_xa));
drm_connector_ida_destroy();
}
@@ -1082,7 +1070,6 @@ static int __init drm_core_init(void)
int ret;
drm_connector_ida_init();
- idr_init(&drm_minors_idr);
drm_memcpy_init_early();
ret = drm_sysfs_init();
