From cdad05216c2b2edfe92a9f87d6ae51aab277f3b2 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Tue, 6 Nov 2012 11:31:50 +0000 Subject: [PATCH] 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 Signed-off-by: Dave Airlie --- 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 c7857874956a..f18eeb458139 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) ? 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); } diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c index 596cef3c9189..292c988c54ea 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); } @@ -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); } diff --git a/include/drm/ttm/ttm_object.h b/include/drm/ttm/ttm_object.h index b01c563b2751..fc0cf0649901 100644 --- a/include/drm/ttm/ttm_object.h +++ b/include/drm/ttm/ttm_object.h @@ -40,6 +40,7 @@ #include #include #include +#include #include /** @@ -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