drm/ttm, drm/vmwgfx: Use RCU locking for object lookups v3
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>
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4b20db3de8
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@ -80,7 +80,7 @@ struct ttm_object_file {
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*/
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struct ttm_object_device {
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rwlock_t object_lock;
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spinlock_t object_lock;
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struct drm_open_hash object_hash;
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atomic_t object_count;
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struct ttm_mem_global *mem_glob;
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@ -157,12 +157,12 @@ int ttm_base_object_init(struct ttm_object_file *tfile,
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base->refcount_release = refcount_release;
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base->ref_obj_release = ref_obj_release;
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base->object_type = object_type;
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write_lock(&tdev->object_lock);
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spin_lock(&tdev->object_lock);
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kref_init(&base->refcount);
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ret = drm_ht_just_insert_please(&tdev->object_hash,
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&base->hash,
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(unsigned long)base, 31, 0, 0);
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write_unlock(&tdev->object_lock);
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spin_unlock(&tdev->object_lock);
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if (unlikely(ret != 0))
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goto out_err0;
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@ -186,30 +186,22 @@ static void ttm_release_base(struct kref *kref)
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container_of(kref, struct ttm_base_object, refcount);
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struct ttm_object_device *tdev = base->tfile->tdev;
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spin_lock(&tdev->object_lock);
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(void)drm_ht_remove_item(&tdev->object_hash, &base->hash);
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write_unlock(&tdev->object_lock);
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spin_unlock(&tdev->object_lock);
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if (base->refcount_release) {
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ttm_object_file_unref(&base->tfile);
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base->refcount_release(&base);
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}
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write_lock(&tdev->object_lock);
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}
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void ttm_base_object_unref(struct ttm_base_object **p_base)
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{
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struct ttm_base_object *base = *p_base;
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struct ttm_object_device *tdev = base->tfile->tdev;
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*p_base = NULL;
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/*
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* Need to take the lock here to avoid racing with
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* users trying to look up the object.
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*/
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write_lock(&tdev->object_lock);
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kref_put(&base->refcount, ttm_release_base);
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write_unlock(&tdev->object_lock);
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}
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EXPORT_SYMBOL(ttm_base_object_unref);
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@ -221,14 +213,14 @@ struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file *tfile,
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struct drm_hash_item *hash;
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int ret;
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read_lock(&tdev->object_lock);
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rcu_read_lock();
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ret = drm_ht_find_item(&tdev->object_hash, key, &hash);
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if (likely(ret == 0)) {
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base = drm_hash_entry(hash, struct ttm_base_object, hash);
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kref_get(&base->refcount);
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ret = kref_get_unless_zero(&base->refcount) ? 0 : -EINVAL;
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}
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read_unlock(&tdev->object_lock);
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rcu_read_unlock();
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if (unlikely(ret != 0))
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return NULL;
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@ -426,7 +418,7 @@ struct ttm_object_device *ttm_object_device_init(struct ttm_mem_global
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return NULL;
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tdev->mem_glob = mem_glob;
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rwlock_init(&tdev->object_lock);
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spin_lock_init(&tdev->object_lock);
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atomic_set(&tdev->object_count, 0);
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ret = drm_ht_create(&tdev->object_hash, hash_order);
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@ -444,9 +436,9 @@ void ttm_object_device_release(struct ttm_object_device **p_tdev)
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*p_tdev = NULL;
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write_lock(&tdev->object_lock);
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spin_lock(&tdev->object_lock);
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drm_ht_remove(&tdev->object_hash);
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write_unlock(&tdev->object_lock);
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spin_unlock(&tdev->object_lock);
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kfree(tdev);
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}
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@ -351,7 +351,7 @@ static void vmw_user_context_free(struct vmw_resource *res)
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container_of(res, struct vmw_user_context, res);
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struct vmw_private *dev_priv = res->dev_priv;
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kfree(ctx);
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ttm_base_object_kfree(ctx, base);
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ttm_mem_global_free(vmw_mem_glob(dev_priv),
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vmw_user_context_size);
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}
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@ -1143,7 +1143,7 @@ static void vmw_user_surface_free(struct vmw_resource *res)
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kfree(srf->offsets);
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kfree(srf->sizes);
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kfree(srf->snooper.image);
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kfree(user_srf);
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ttm_base_object_kfree(user_srf, base);
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ttm_mem_global_free(vmw_mem_glob(dev_priv), size);
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}
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@ -1571,7 +1571,7 @@ static void vmw_user_dmabuf_destroy(struct ttm_buffer_object *bo)
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{
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struct vmw_user_dma_buffer *vmw_user_bo = vmw_user_dma_buffer(bo);
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kfree(vmw_user_bo);
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ttm_base_object_kfree(vmw_user_bo, base);
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}
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static void vmw_user_dmabuf_release(struct ttm_base_object **p_base)
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@ -1759,7 +1759,7 @@ static void vmw_user_stream_free(struct vmw_resource *res)
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container_of(res, struct vmw_user_stream, stream.res);
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struct vmw_private *dev_priv = res->dev_priv;
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kfree(stream);
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ttm_base_object_kfree(stream, base);
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ttm_mem_global_free(vmw_mem_glob(dev_priv),
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vmw_user_stream_size);
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}
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@ -40,6 +40,7 @@
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#include <linux/list.h>
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#include <drm/drm_hashtab.h>
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#include <linux/kref.h>
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#include <linux/rcupdate.h>
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#include <ttm/ttm_memory.h>
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/**
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@ -120,6 +121,7 @@ struct ttm_object_device;
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*/
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struct ttm_base_object {
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struct rcu_head rhead;
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struct drm_hash_item hash;
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enum ttm_object_type object_type;
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bool shareable;
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@ -268,4 +270,6 @@ extern struct ttm_object_device *ttm_object_device_init
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extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
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#define ttm_base_object_kfree(__object, __base)\
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kfree_rcu(__object, __base.rhead)
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#endif
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