There is no reason to use a heavy mutex for idr protection. Use a spinlock
and make idr-allocation use idr_preload().
This patch also makes mode-object lookup irq-save, in case you ever wanna
lookup modeset objects from interrupts. This is just a side-effect of
avoiding a mutex.
Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
---
drivers/gpu/drm/drm_crtc.c | 34 ++++++++++++++++++++--------------
include/drm/drm_crtc.h | 4 ++--
2 files changed, 22 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 61b6978..97eba56 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -283,8 +283,10 @@ static int drm_mode_object_get_reg(struct drm_device *dev,
{
int ret;
- mutex_lock(&dev->mode_config.idr_mutex);
- ret = idr_alloc(&dev->mode_config.crtc_idr, register_obj ? obj : NULL,
1, 0, GFP_KERNEL);
+ idr_preload(GFP_KERNEL);
+ spin_lock_irq(&dev->mode_config.idr_lock);
+
+ ret = idr_alloc(&dev->mode_config.crtc_idr, register_obj ? obj : NULL,
1, 0, GFP_NOWAIT);
if (ret >= 0) {
/*
* Set up the object linking under the protection of the idr
@@ -293,7 +295,9 @@ static int drm_mode_object_get_reg(struct drm_device *dev,
obj->id = ret;
obj->type = obj_type;
}
- mutex_unlock(&dev->mode_config.idr_mutex);
+
+ spin_unlock_irq(&dev->mode_config.idr_lock);
+ idr_preload_end();
return ret < 0 ? ret : 0;
}
@@ -322,9 +326,9 @@ int drm_mode_object_get(struct drm_device *dev,
static void drm_mode_object_register(struct drm_device *dev,
struct drm_mode_object *obj)
{
- mutex_lock(&dev->mode_config.idr_mutex);
+ spin_lock_irq(&dev->mode_config.idr_lock);
idr_replace(&dev->mode_config.crtc_idr, obj, obj->id);
- mutex_unlock(&dev->mode_config.idr_mutex);
+ spin_unlock_irq(&dev->mode_config.idr_lock);
}
/**
@@ -339,17 +343,18 @@ static void drm_mode_object_register(struct drm_device
*dev,
void drm_mode_object_put(struct drm_device *dev,
struct drm_mode_object *object)
{
- mutex_lock(&dev->mode_config.idr_mutex);
+ spin_lock_irq(&dev->mode_config.idr_lock);
idr_remove(&dev->mode_config.crtc_idr, object->id);
- mutex_unlock(&dev->mode_config.idr_mutex);
+ spin_unlock_irq(&dev->mode_config.idr_lock);
}
static struct drm_mode_object *_object_find(struct drm_device *dev,
uint32_t id, uint32_t type)
{
struct drm_mode_object *obj = NULL;
+ unsigned long flags;
- mutex_lock(&dev->mode_config.idr_mutex);
+ spin_lock_irqsave(&dev->mode_config.idr_lock, flags);
obj = idr_find(&dev->mode_config.crtc_idr, id);
if (obj && type != DRM_MODE_OBJECT_ANY && obj->type != type)
obj = NULL;
@@ -358,7 +363,7 @@ static struct drm_mode_object *_object_find(struct
drm_device *dev,
/* don't leak out unref'd fb's */
if (obj && (obj->type == DRM_MODE_OBJECT_FB))
obj = NULL;
- mutex_unlock(&dev->mode_config.idr_mutex);
+ spin_unlock_irqrestore(&dev->mode_config.idr_lock, flags);
return obj;
}
@@ -433,9 +438,9 @@ EXPORT_SYMBOL(drm_framebuffer_init);
static void __drm_framebuffer_unregister(struct drm_device *dev,
struct drm_framebuffer *fb)
{
- mutex_lock(&dev->mode_config.idr_mutex);
+ spin_lock_irq(&dev->mode_config.idr_lock);
idr_remove(&dev->mode_config.crtc_idr, fb->base.id);
- mutex_unlock(&dev->mode_config.idr_mutex);
+ spin_unlock_irq(&dev->mode_config.idr_lock);
fb->base.id = 0;
}
@@ -465,14 +470,15 @@ static struct drm_framebuffer
*__drm_framebuffer_lookup(struct drm_device *dev,
{
struct drm_mode_object *obj = NULL;
struct drm_framebuffer *fb;
+ unsigned long flags;
- mutex_lock(&dev->mode_config.idr_mutex);
+ spin_lock_irqsave(&dev->mode_config.idr_lock, flags);
obj = idr_find(&dev->mode_config.crtc_idr, id);
if (!obj || (obj->type != DRM_MODE_OBJECT_FB) || (obj->id != id))
fb = NULL;
else
fb = obj_to_fb(obj);
- mutex_unlock(&dev->mode_config.idr_mutex);
+ spin_unlock_irqrestore(&dev->mode_config.idr_lock, flags);
return fb;
}
@@ -5049,7 +5055,7 @@ void drm_mode_config_init(struct drm_device *dev)
{
mutex_init(&dev->mode_config.mutex);
drm_modeset_lock_init(&dev->mode_config.connection_mutex);
- mutex_init(&dev->mode_config.idr_mutex);
+ spin_lock_init(&dev->mode_config.idr_lock);
mutex_init(&dev->mode_config.fb_lock);
INIT_LIST_HEAD(&dev->mode_config.fb_list);
INIT_LIST_HEAD(&dev->mode_config.crtc_list);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 77d9763..9c57b56 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -742,7 +742,7 @@ struct drm_mode_group {
/**
* drm_mode_config - Mode configuration control structure
* @mutex: mutex protecting KMS related lists and structures
- * @idr_mutex: mutex for KMS ID allocation and management
+ * @idr_lock: lock for KMS ID allocation and management
* @crtc_idr: main KMS ID tracking object
* @num_fb: number of fbs available
* @fb_list: list of framebuffers available
@@ -772,7 +772,7 @@ struct drm_mode_config {
struct mutex mutex; /* protects configuration (mode lists etc.) */
struct drm_modeset_lock connection_mutex; /* protects
connector->encoder and encoder->crtc links */
struct drm_modeset_acquire_ctx *acquire_ctx; /* for legacy _lock_all()
/ _unlock_all() */
- struct mutex idr_mutex; /* for IDR management */
+ spinlock_t idr_lock; /* for IDR management */
struct idr crtc_idr; /* use this idr for all IDs, fb, crtc, connector,
modes - just makes life easier */
/* this is limited to one for now */
--
2.1.0
