On 2023-07-24 17:14, Michał Winiarski
wrote:
[JZ] would WARN_ON(entry != minor)be better?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. Signed-off-by: Michał Winiarski <michal.winiarski@xxxxxxxxx> Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> --- drivers/gpu/drm/drm_drv.c | 63 ++++++++++++++++----------------------- 1 file changed, 25 insertions(+), 38 deletions(-) diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index 3eda026ffac6..3faecb01186f 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);
[JZ] why minor->dev need ca_lock here?
- spin_unlock_irqrestore(&drm_minor_lock, flags);
+ xa_unlock(&drm_minors_xa);
if (!minor) {
return ERR_PTR(-ENODEV);
@@ -1067,7 +1055,7 @@ static void drm_core_exit(void)
unregister_chrdev(DRM_MAJOR, "drm");
debugfs_remove(drm_debugfs_root);
drm_sysfs_destroy();
- idr_destroy(&drm_minors_idr);
[JZ] Should we call xa_destroy instead here?
+ WARN_ON(!xa_empty(&drm_minors_xa)); drm_connector_ida_destroy(); } @@ -1076,7 +1064,6 @@ 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();
