[PATCH 3/4] drm/ttm, drm/vmwgfx: Use RCU locking for object lookups v2
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
Signed-off-by: Thomas Hellstrom
---
drivers/gpu/drm/ttm/ttm_object.c | 30 +++---
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c |8
include/drm/ttm/ttm_object.h |4
3 files changed, 19 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c
index c785787..9d7f674 100644
--- a/drivers/gpu/drm/ttm/ttm_object.c
+++ b/drivers/gpu/drm/ttm/ttm_object.c
@@ -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(>object_lock);
+ spin_lock(>object_lock);
kref_init(>refcount);
ret = drm_ht_just_insert_please(>object_hash,
>hash,
(unsigned long)base, 31, 0, 0);
- write_unlock(>object_lock);
+ spin_unlock(>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(>object_lock);
(void)drm_ht_remove_item(>object_hash, >hash);
- write_unlock(>object_lock);
+ spin_unlock(>object_lock);
if (base->refcount_release) {
ttm_object_file_unref(>tfile);
base->refcount_release();
}
- write_lock(>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(>object_lock);
kref_put(>refcount, ttm_release_base);
- write_unlock(>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(>object_lock);
+ rcu_read_lock();
ret = drm_ht_find_item(>object_hash, key, );
if (likely(ret == 0)) {
base = drm_hash_entry(hash, struct ttm_base_object, hash);
- kref_get(>refcount);
+ ret = kref_get_unless_zero(>refcount);
}
- read_unlock(>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(>object_lock);
+ spin_lock_init(>object_lock);
atomic_set(>object_count, 0);
ret = drm_ht_create(>object_hash, hash_order);
@@ -444,9 +436,9 @@ void ttm_object_device_release(struct ttm_object_device
**p_tdev)
*p_tdev = NULL;
- write_lock(>object_lock);
+ spin_lock(>object_lock);
drm_ht_remove(>object_hash);
- write_unlock(>object_lock);
+ spin_unlock(>object_lock);
kfree(tdev);
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index da3c6b5..ae675c6 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -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);
}
@@ -1147,7 +1147,7 @@ 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);
}
@@ -1575,7 +1575,7 @@ static void vmw_user_dmabuf_destroy(struct
ttm_buffer_object *bo)
{
struct vmw_user_dma_buffer *vmw_user_bo = vmw_user_dma_buffer(bo);
[PATCH 3/4] drm/ttm, drm/vmwgfx: Use RCU locking for object lookups v2
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
Signed-off-by: Thomas Hellstrom thellst...@vmware.com
---
drivers/gpu/drm/ttm/ttm_object.c | 30 +++---
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c |8
include/drm/ttm/ttm_object.h |4
3 files changed, 19 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c
index c785787..9d7f674 100644
--- a/drivers/gpu/drm/ttm/ttm_object.c
+++ b/drivers/gpu/drm/ttm/ttm_object.c
@@ -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);
}
- 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);
}
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index da3c6b5..ae675c6 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -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);
}
@@ -1147,7 +1147,7 @@ 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);
}
@@ -1575,7
