redonkable/remarkable-linux
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drm/ttm, drm/vmwgfx: Use RCU locking for object lookups v3

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The mostly used lookup+get put+potential_destroy path of TTM objects
is converted to use RCU locks. This will substantially decrease the amount
of locked bus cycles during normal operation.
Since we use kfree_rcu to free the objects, no rcu synchronization is needed
at module unload time.

v2: Don't touch include/linux/kref.h
v3: Adapt to kref_get_unless_zero return value change

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Thomas Hellstrom 2012-11-06 11:31:50 +00:00 committed by Dave Airlie
parent 4b20db3de8
commit cdad05216c
3 changed files with 19 additions and 23 deletions
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30
drivers/gpu/drm/ttm/ttm_object.c
View file

@ -80,7 +80,7 @@ struct ttm_object_file {
*/
struct ttm_object_device {
rwlock_t object_lock;
spinlock_t object_lock;
struct drm_open_hash object_hash;
atomic_t object_count;
struct ttm_mem_global *mem_glob;
@ -157,12 +157,12 @@ int ttm_base_object_init(struct ttm_object_file *tfile,
base->refcount_release = refcount_release;
base->ref_obj_release = ref_obj_release;
base->object_type = object_type;
write_lock(&tdev->object_lock);
spin_lock(&tdev->object_lock);
kref_init(&base->refcount);
ret = drm_ht_just_insert_please(&tdev->object_hash,
&base->hash,
(unsigned long)base, 31, 0, 0);
write_unlock(&tdev->object_lock);
spin_unlock(&tdev->object_lock);
if (unlikely(ret != 0))
goto out_err0;
@ -186,30 +186,22 @@ static void ttm_release_base(struct kref *kref)
container_of(kref, struct ttm_base_object, refcount);
struct ttm_object_device *tdev = base->tfile->tdev;
spin_lock(&tdev->object_lock);
(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
write_unlock(&tdev->object_lock);
spin_unlock(&tdev->object_lock);
if (base->refcount_release) {
ttm_object_file_unref(&base->tfile);
base->refcount_release(&base);
}
write_lock(&tdev->object_lock);
}
void ttm_base_object_unref(struct ttm_base_object **p_base)
{
struct ttm_base_object *base = *p_base;
struct ttm_object_device *tdev = base->tfile->tdev;
*p_base = NULL;
/*
* Need to take the lock here to avoid racing with
* users trying to look up the object.
*/
write_lock(&tdev->object_lock);
kref_put(&base->refcount, ttm_release_base);
write_unlock(&tdev->object_lock);
}
EXPORT_SYMBOL(ttm_base_object_unref);
@ -221,14 +213,14 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
struct drm_hash_item *hash;
int ret;
read_lock(&tdev->object_lock);
rcu_read_lock();
ret = drm_ht_find_item(&tdev->object_hash, key, &hash);
if (likely(ret == 0)) {
base = drm_hash_entry(hash, struct ttm_base_object, hash);
kref_get(&base->refcount);
ret = kref_get_unless_zero(&base->refcount) ? 0 : -EINVAL;
}
read_unlock(&tdev->object_lock);
rcu_read_unlock();
if (unlikely(ret != 0))
return NULL;
@ -426,7 +418,7 @@ struct ttm_object_device *ttm_object_device_init(struct ttm_mem_global
return NULL;
tdev->mem_glob = mem_glob;
rwlock_init(&tdev->object_lock);
spin_lock_init(&tdev->object_lock);
atomic_set(&tdev->object_count, 0);
ret = drm_ht_create(&tdev->object_hash, hash_order);
@ -444,9 +436,9 @@ void ttm_object_device_release(struct ttm_object_device **p_tdev)
*p_tdev = NULL;
write_lock(&tdev->object_lock);
spin_lock(&tdev->object_lock);
drm_ht_remove(&tdev->object_hash);
write_unlock(&tdev->object_lock);
spin_unlock(&tdev->object_lock);
kfree(tdev);
}

8
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
View file

@ -351,7 +351,7 @@ static void vmw_user_context_free(struct vmw_resource *res)
container_of(res, struct vmw_user_context, res);
struct vmw_private *dev_priv = res->dev_priv;
kfree(ctx);
ttm_base_object_kfree(ctx, base);
ttm_mem_global_free(vmw_mem_glob(dev_priv),
vmw_user_context_size);
}
@ -1143,7 +1143,7 @@ static void vmw_user_surface_free(struct vmw_resource *res)
kfree(srf->offsets);
kfree(srf->sizes);
kfree(srf->snooper.image);
kfree(user_srf);
ttm_base_object_kfree(user_srf, base);
ttm_mem_global_free(vmw_mem_glob(dev_priv), size);
}
@ -1571,7 +1571,7 @@ static void vmw_user_dmabuf_destroy(struct ttm_buffer_object *bo)
{
struct vmw_user_dma_buffer *vmw_user_bo = vmw_user_dma_buffer(bo);
kfree(vmw_user_bo);
ttm_base_object_kfree(vmw_user_bo, base);
}
static void vmw_user_dmabuf_release(struct ttm_base_object **p_base)
@ -1759,7 +1759,7 @@ static void vmw_user_stream_free(struct vmw_resource *res)
container_of(res, struct vmw_user_stream, stream.res);
struct vmw_private *dev_priv = res->dev_priv;
kfree(stream);
ttm_base_object_kfree(stream, base);
ttm_mem_global_free(vmw_mem_glob(dev_priv),
vmw_user_stream_size);
}

4
include/drm/ttm/ttm_object.h
View file

@ -40,6 +40,7 @@
#include <linux/list.h>
#include <drm/drm_hashtab.h>
#include <linux/kref.h>
#include <linux/rcupdate.h>
#include <ttm/ttm_memory.h>
/**
@ -120,6 +121,7 @@ struct ttm_object_device;
*/
struct ttm_base_object {
struct rcu_head rhead;
struct drm_hash_item hash;
enum ttm_object_type object_type;
bool shareable;
@ -268,4 +270,6 @@ extern struct ttm_object_device *ttm_object_device_init
extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
#define ttm_base_object_kfree(__object, __base)\
kfree_rcu(__object, __base.rhead)
#endif