From 43cf1fc0e27e2f7eeb5d6c15fd023813a5b49987 Mon Sep 17 00:00:00 2001 From: Chunming Zhou Date: Tue, 23 Oct 2018 17:37:45 +0800 Subject: [PATCH] drm: fix deadlock of syncobj v6 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit v2: add a mutex between sync_cb execution and free. v3: clearly separating the roles for pt_lock and cb_mutex (Chris) v4: the cb_mutex should be taken outside of the pt_lock around this if() block. (Chris) v5: fix a corner case v6: tidy drm_syncobj_fence_get_or_add_callback up. (Chris) Tested by syncobj_basic and syncobj_wait of igt. Signed-off-by: Chunming Zhou Cc: Daniel Vetter Cc: Chris Wilson Cc: Christian König Cc: intel-gfx@lists.freedesktop.org Reviewed-by: Chris Wilson Signed-off-by: Christian König Link: https://patchwork.kernel.org/patch/10652893/ --- drivers/gpu/drm/drm_syncobj.c | 156 ++++++++++++++++------------------ include/drm/drm_syncobj.h | 8 +- 2 files changed, 81 insertions(+), 83 deletions(-) diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 57bf6006394d..b7eaa603f368 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -106,6 +106,42 @@ struct drm_syncobj *drm_syncobj_find(struct drm_file *file_private, } EXPORT_SYMBOL(drm_syncobj_find); +static struct dma_fence +*drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj, + uint64_t point) +{ + struct drm_syncobj_signal_pt *signal_pt; + + if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) && + (point <= syncobj->timeline)) { + struct drm_syncobj_stub_fence *fence = + kzalloc(sizeof(struct drm_syncobj_stub_fence), + GFP_KERNEL); + + if (!fence) + return NULL; + spin_lock_init(&fence->lock); + dma_fence_init(&fence->base, + &drm_syncobj_stub_fence_ops, + &fence->lock, + syncobj->timeline_context, + point); + + dma_fence_signal(&fence->base); + return &fence->base; + } + + list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) { + if (point > signal_pt->value) + continue; + if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) && + (point != signal_pt->value)) + continue; + return dma_fence_get(&signal_pt->fence_array->base); + } + return NULL; +} + static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj, struct drm_syncobj_cb *cb, drm_syncobj_func_t func) @@ -114,115 +150,71 @@ static void drm_syncobj_add_callback_locked(struct drm_syncobj *syncobj, list_add_tail(&cb->node, &syncobj->cb_list); } -static int drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj, - struct dma_fence **fence, - struct drm_syncobj_cb *cb, - drm_syncobj_func_t func) +static void drm_syncobj_fence_get_or_add_callback(struct drm_syncobj *syncobj, + struct dma_fence **fence, + struct drm_syncobj_cb *cb, + drm_syncobj_func_t func) { - int ret; + u64 pt_value = 0; - ret = drm_syncobj_search_fence(syncobj, 0, 0, fence); - if (!ret) - return 1; + if (syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) { + /*BINARY syncobj always wait on last pt */ + pt_value = syncobj->signal_point; - spin_lock(&syncobj->lock); - /* We've already tried once to get a fence and failed. Now that we - * have the lock, try one more time just to be sure we don't add a - * callback when a fence has already been set. - */ - if (!list_empty(&syncobj->signal_pt_list)) { - spin_unlock(&syncobj->lock); - drm_syncobj_search_fence(syncobj, 0, 0, fence); - if (*fence) - return 1; - spin_lock(&syncobj->lock); - } else { - *fence = NULL; - drm_syncobj_add_callback_locked(syncobj, cb, func); - ret = 0; + if (pt_value == 0) + pt_value += DRM_SYNCOBJ_BINARY_POINT; } - spin_unlock(&syncobj->lock); - return ret; + mutex_lock(&syncobj->cb_mutex); + spin_lock(&syncobj->pt_lock); + *fence = drm_syncobj_find_signal_pt_for_point(syncobj, pt_value); + spin_unlock(&syncobj->pt_lock); + if (!*fence) + drm_syncobj_add_callback_locked(syncobj, cb, func); + mutex_unlock(&syncobj->cb_mutex); } void drm_syncobj_add_callback(struct drm_syncobj *syncobj, struct drm_syncobj_cb *cb, drm_syncobj_func_t func) { - spin_lock(&syncobj->lock); + mutex_lock(&syncobj->cb_mutex); drm_syncobj_add_callback_locked(syncobj, cb, func); - spin_unlock(&syncobj->lock); + mutex_unlock(&syncobj->cb_mutex); } void drm_syncobj_remove_callback(struct drm_syncobj *syncobj, struct drm_syncobj_cb *cb) { - spin_lock(&syncobj->lock); + mutex_lock(&syncobj->cb_mutex); list_del_init(&cb->node); - spin_unlock(&syncobj->lock); + mutex_unlock(&syncobj->cb_mutex); } static void drm_syncobj_init(struct drm_syncobj *syncobj) { - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); syncobj->timeline_context = dma_fence_context_alloc(1); syncobj->timeline = 0; syncobj->signal_point = 0; init_waitqueue_head(&syncobj->wq); INIT_LIST_HEAD(&syncobj->signal_pt_list); - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); } static void drm_syncobj_fini(struct drm_syncobj *syncobj) { struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp; - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); list_for_each_entry_safe(signal_pt, tmp, &syncobj->signal_pt_list, list) { list_del(&signal_pt->list); dma_fence_put(&signal_pt->fence_array->base); kfree(signal_pt); } - spin_unlock(&syncobj->lock); -} - -static struct dma_fence -*drm_syncobj_find_signal_pt_for_point(struct drm_syncobj *syncobj, - uint64_t point) -{ - struct drm_syncobj_signal_pt *signal_pt; - - if ((syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) && - (point <= syncobj->timeline)) { - struct drm_syncobj_stub_fence *fence = - kzalloc(sizeof(struct drm_syncobj_stub_fence), - GFP_KERNEL); - - if (!fence) - return NULL; - spin_lock_init(&fence->lock); - dma_fence_init(&fence->base, - &drm_syncobj_stub_fence_ops, - &fence->lock, - syncobj->timeline_context, - point); - - dma_fence_signal(&fence->base); - return &fence->base; - } - - list_for_each_entry(signal_pt, &syncobj->signal_pt_list, list) { - if (point > signal_pt->value) - continue; - if ((syncobj->type == DRM_SYNCOBJ_TYPE_BINARY) && - (point != signal_pt->value)) - continue; - return dma_fence_get(&signal_pt->fence_array->base); - } - return NULL; + spin_unlock(&syncobj->pt_lock); } static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj, @@ -249,14 +241,14 @@ static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj, fences[num_fences++] = dma_fence_get(fence); /* timeline syncobj must take this dependency */ if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) { - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); if (!list_empty(&syncobj->signal_pt_list)) { tail_pt = list_last_entry(&syncobj->signal_pt_list, struct drm_syncobj_signal_pt, list); fences[num_fences++] = dma_fence_get(&tail_pt->fence_array->base); } - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); } signal_pt->fence_array = dma_fence_array_create(num_fences, fences, syncobj->timeline_context, @@ -266,16 +258,16 @@ static int drm_syncobj_create_signal_pt(struct drm_syncobj *syncobj, goto fail; } - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); if (syncobj->signal_point >= point) { DRM_WARN("A later signal is ready!"); - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); goto exist; } signal_pt->value = point; list_add_tail(&signal_pt->list, &syncobj->signal_pt_list); syncobj->signal_point = point; - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); wake_up_all(&syncobj->wq); return 0; @@ -294,7 +286,7 @@ static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj) { struct drm_syncobj_signal_pt *signal_pt, *tmp, *tail_pt; - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); tail_pt = list_last_entry(&syncobj->signal_pt_list, struct drm_syncobj_signal_pt, list); @@ -315,7 +307,7 @@ static void drm_syncobj_garbage_collection(struct drm_syncobj *syncobj) } } - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); } /** * drm_syncobj_replace_fence - replace fence in a sync object. @@ -344,13 +336,14 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj, drm_syncobj_create_signal_pt(syncobj, fence, pt_value); if (fence) { struct drm_syncobj_cb *cur, *tmp; + LIST_HEAD(cb_list); - spin_lock(&syncobj->lock); + mutex_lock(&syncobj->cb_mutex); list_for_each_entry_safe(cur, tmp, &syncobj->cb_list, node) { list_del_init(&cur->node); cur->func(syncobj, cur); } - spin_unlock(&syncobj->lock); + mutex_unlock(&syncobj->cb_mutex); } } EXPORT_SYMBOL(drm_syncobj_replace_fence); @@ -386,11 +379,11 @@ drm_syncobj_point_get(struct drm_syncobj *syncobj, u64 point, u64 flags, if (ret < 0) return ret; } - spin_lock(&syncobj->lock); + spin_lock(&syncobj->pt_lock); *fence = drm_syncobj_find_signal_pt_for_point(syncobj, point); if (!*fence) ret = -EINVAL; - spin_unlock(&syncobj->lock); + spin_unlock(&syncobj->pt_lock); return ret; } @@ -500,7 +493,8 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags, kref_init(&syncobj->refcount); INIT_LIST_HEAD(&syncobj->cb_list); - spin_lock_init(&syncobj->lock); + spin_lock_init(&syncobj->pt_lock); + mutex_init(&syncobj->cb_mutex); if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE; else diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h index 5e8c5c027e09..29244cbcd05e 100644 --- a/include/drm/drm_syncobj.h +++ b/include/drm/drm_syncobj.h @@ -75,9 +75,13 @@ struct drm_syncobj { */ struct list_head cb_list; /** - * @lock: Protects syncobj list and write-locks &fence. + * @pt_lock: Protects pt list. */ - spinlock_t lock; + spinlock_t pt_lock; + /** + * @cb_mutex: Protects syncobj cb list. + */ + struct mutex cb_mutex; /** * @file: A file backing for this syncobj. */ -- 2.30.2