From patchwork Thu Dec 29 06:55:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Reshetova, Elena" X-Patchwork-Id: 9491039 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4204460488 for ; Thu, 29 Dec 2016 06:57:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 31AA31FF65 for ; Thu, 29 Dec 2016 06:57:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 26216209CD; Thu, 29 Dec 2016 06:57:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 32C6E1FF65 for ; Thu, 29 Dec 2016 06:57:00 +0000 (UTC) Received: (qmail 21842 invoked by uid 550); 29 Dec 2016 06:56:44 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 21754 invoked from network); 29 Dec 2016 06:56:43 -0000 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.33,425,1477983600"; d="scan'208";a="803215608" From: Elena Reshetova To: kernel-hardening@lists.openwall.com Cc: keescook@chromium.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, h.peter.anvin@intel.com, peterz@infradead.org, will.deacon@arm.com, dwindsor@gmail.com, gregkh@linuxfoundation.org, ishkamiel@gmail.com, Elena Reshetova Date: Thu, 29 Dec 2016 08:55:54 +0200 Message-Id: <1482994571-18687-3-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1482994571-18687-1-git-send-email-elena.reshetova@intel.com> References: <1482994571-18687-1-git-send-email-elena.reshetova@intel.com> Subject: [kernel-hardening] [RFC PATCH 02/19] By general sentiment kref_sub() is a bad interface, make it go away. X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Peter Zijlstra (Intel) --- drivers/block/drbd/drbd_main.c | 7 ++-- drivers/block/drbd/drbd_req.c | 31 ++++++------------ drivers/gpu/drm/ttm/ttm_bo.c | 59 +++++++++------------------------- drivers/gpu/drm/ttm/ttm_execbuf_util.c | 4 +-- include/drm/ttm/ttm_bo_api.h | 15 +-------- include/linux/kref.h | 32 +++--------------- 6 files changed, 36 insertions(+), 112 deletions(-) diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index 8348272..c3ff60c 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -2948,7 +2948,6 @@ void drbd_delete_device(struct drbd_device *device) struct drbd_resource *resource = device->resource; struct drbd_connection *connection; struct drbd_peer_device *peer_device; - int refs = 3; /* move to free_peer_device() */ for_each_peer_device(peer_device, device) @@ -2956,13 +2955,15 @@ void drbd_delete_device(struct drbd_device *device) drbd_debugfs_device_cleanup(device); for_each_connection(connection, resource) { idr_remove(&connection->peer_devices, device->vnr); - refs++; + kref_put(&device->kref, drbd_destroy_device); } idr_remove(&resource->devices, device->vnr); + kref_put(&device->kref, drbd_destroy_device); idr_remove(&drbd_devices, device_to_minor(device)); + kref_put(&device->kref, drbd_destroy_device); del_gendisk(device->vdisk); synchronize_rcu(); - kref_sub(&device->kref, refs, drbd_destroy_device); + kref_put(&device->kref, drbd_destroy_device); } static int __init drbd_init(void) diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 74306c0..b489ac2 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -421,7 +421,6 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, struct drbd_peer_device *peer_device = first_peer_device(device); unsigned s = req->rq_state; int c_put = 0; - int k_put = 0; if (drbd_suspended(device) && !((s | clear) & RQ_COMPLETION_SUSP)) set |= RQ_COMPLETION_SUSP; @@ -437,6 +436,8 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, /* intent: get references */ + kref_get(&req->kref); + if (!(s & RQ_LOCAL_PENDING) && (set & RQ_LOCAL_PENDING)) atomic_inc(&req->completion_ref); @@ -473,15 +474,12 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, if (!(s & RQ_LOCAL_ABORTED) && (set & RQ_LOCAL_ABORTED)) { D_ASSERT(device, req->rq_state & RQ_LOCAL_PENDING); - /* local completion may still come in later, - * we need to keep the req object around. */ - kref_get(&req->kref); ++c_put; } if ((s & RQ_LOCAL_PENDING) && (clear & RQ_LOCAL_PENDING)) { if (req->rq_state & RQ_LOCAL_ABORTED) - ++k_put; + kref_put(&req->kref, drbd_req_destroy); else ++c_put; list_del_init(&req->req_pending_local); @@ -503,7 +501,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, if (s & RQ_NET_SENT) atomic_sub(req->i.size >> 9, &device->ap_in_flight); if (s & RQ_EXP_BARR_ACK) - ++k_put; + kref_put(&req->kref, drbd_req_destroy); req->net_done_jif = jiffies; /* in ahead/behind mode, or just in case, @@ -516,25 +514,16 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m, /* potentially complete and destroy */ - if (k_put || c_put) { - /* Completion does it's own kref_put. If we are going to - * kref_sub below, we need req to be still around then. */ - int at_least = k_put + !!c_put; - int refcount = kref_read(&req->kref); - if (refcount < at_least) - drbd_err(device, - "mod_rq_state: Logic BUG: %x -> %x: refcount = %d, should be >= %d\n", - s, req->rq_state, refcount, at_least); - } - /* If we made progress, retry conflicting peer requests, if any. */ if (req->i.waiting) wake_up(&device->misc_wait); - if (c_put) - k_put += drbd_req_put_completion_ref(req, m, c_put); - if (k_put) - kref_sub(&req->kref, k_put, drbd_req_destroy); + if (c_put) { + if (drbd_req_put_completion_ref(req, m, c_put)) + kref_put(&req->kref, drbd_req_destroy); + } else { + kref_put(&req->kref, drbd_req_destroy); + } } static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req) diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index 30aefcc..ffc6cb5 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -181,61 +181,46 @@ void ttm_bo_add_to_lru(struct ttm_buffer_object *bo) } EXPORT_SYMBOL(ttm_bo_add_to_lru); -int ttm_bo_del_from_lru(struct ttm_buffer_object *bo) +static void ttm_bo_ref_bug(struct kref *list_kref) +{ + BUG(); +} + +void ttm_bo_del_from_lru(struct ttm_buffer_object *bo) { struct ttm_bo_device *bdev = bo->bdev; - int put_count = 0; if (bdev->driver->lru_removal) bdev->driver->lru_removal(bo); if (!list_empty(&bo->swap)) { list_del_init(&bo->swap); - ++put_count; + kref_put(&bo->list_kref, ttm_bo_ref_bug); } if (!list_empty(&bo->lru)) { list_del_init(&bo->lru); - ++put_count; + kref_put(&bo->list_kref, ttm_bo_ref_bug); } - - return put_count; -} - -static void ttm_bo_ref_bug(struct kref *list_kref) -{ - BUG(); -} - -void ttm_bo_list_ref_sub(struct ttm_buffer_object *bo, int count, - bool never_free) -{ - kref_sub(&bo->list_kref, count, - (never_free) ? ttm_bo_ref_bug : ttm_bo_release_list); } void ttm_bo_del_sub_from_lru(struct ttm_buffer_object *bo) { - int put_count; - spin_lock(&bo->glob->lru_lock); - put_count = ttm_bo_del_from_lru(bo); + ttm_bo_del_from_lru(bo); spin_unlock(&bo->glob->lru_lock); - ttm_bo_list_ref_sub(bo, put_count, true); } EXPORT_SYMBOL(ttm_bo_del_sub_from_lru); void ttm_bo_move_to_lru_tail(struct ttm_buffer_object *bo) { struct ttm_bo_device *bdev = bo->bdev; - int put_count = 0; lockdep_assert_held(&bo->resv->lock.base); if (bdev->driver->lru_removal) bdev->driver->lru_removal(bo); - put_count = ttm_bo_del_from_lru(bo); - ttm_bo_list_ref_sub(bo, put_count, true); + ttm_bo_del_from_lru(bo); ttm_bo_add_to_lru(bo); } EXPORT_SYMBOL(ttm_bo_move_to_lru_tail); @@ -447,7 +432,6 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo) { struct ttm_bo_device *bdev = bo->bdev; struct ttm_bo_global *glob = bo->glob; - int put_count; int ret; spin_lock(&glob->lru_lock); @@ -455,13 +439,10 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo) if (!ret) { if (!ttm_bo_wait(bo, false, true)) { - put_count = ttm_bo_del_from_lru(bo); - + ttm_bo_del_from_lru(bo); spin_unlock(&glob->lru_lock); ttm_bo_cleanup_memtype_use(bo); - ttm_bo_list_ref_sub(bo, put_count, true); - return; } else ttm_bo_flush_all_fences(bo); @@ -504,7 +485,6 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo, bool no_wait_gpu) { struct ttm_bo_global *glob = bo->glob; - int put_count; int ret; ret = ttm_bo_wait(bo, false, true); @@ -554,15 +534,13 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo, return ret; } - put_count = ttm_bo_del_from_lru(bo); + ttm_bo_del_from_lru(bo); list_del_init(&bo->ddestroy); - ++put_count; + kref_put(&bo->list_kref, ttm_bo_ref_bug); spin_unlock(&glob->lru_lock); ttm_bo_cleanup_memtype_use(bo); - ttm_bo_list_ref_sub(bo, put_count, true); - return 0; } @@ -740,7 +718,7 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev, struct ttm_bo_global *glob = bdev->glob; struct ttm_mem_type_manager *man = &bdev->man[mem_type]; struct ttm_buffer_object *bo; - int ret = -EBUSY, put_count; + int ret = -EBUSY; spin_lock(&glob->lru_lock); list_for_each_entry(bo, &man->lru, lru) { @@ -771,13 +749,11 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev, return ret; } - put_count = ttm_bo_del_from_lru(bo); + ttm_bo_del_from_lru(bo); spin_unlock(&glob->lru_lock); BUG_ON(ret != 0); - ttm_bo_list_ref_sub(bo, put_count, true); - ret = ttm_bo_evict(bo, interruptible, no_wait_gpu); ttm_bo_unreserve(bo); @@ -1669,7 +1645,6 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink) container_of(shrink, struct ttm_bo_global, shrink); struct ttm_buffer_object *bo; int ret = -EBUSY; - int put_count; uint32_t swap_placement = (TTM_PL_FLAG_CACHED | TTM_PL_FLAG_SYSTEM); spin_lock(&glob->lru_lock); @@ -1692,11 +1667,9 @@ static int ttm_bo_swapout(struct ttm_mem_shrink *shrink) return ret; } - put_count = ttm_bo_del_from_lru(bo); + ttm_bo_del_from_lru(bo); spin_unlock(&glob->lru_lock); - ttm_bo_list_ref_sub(bo, put_count, true); - /** * Move to system cached */ diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c index d35bc49..5e1bcab 100644 --- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c +++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c @@ -48,9 +48,7 @@ static void ttm_eu_del_from_lru_locked(struct list_head *list) list_for_each_entry(entry, list, head) { struct ttm_buffer_object *bo = entry->bo; - unsigned put_count = ttm_bo_del_from_lru(bo); - - ttm_bo_list_ref_sub(bo, put_count, true); + ttm_bo_del_from_lru(bo); } } diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h index 652e45b..9a46531 100644 --- a/include/drm/ttm/ttm_bo_api.h +++ b/include/drm/ttm/ttm_bo_api.h @@ -332,19 +332,6 @@ extern int ttm_bo_validate(struct ttm_buffer_object *bo, */ extern void ttm_bo_unref(struct ttm_buffer_object **bo); - -/** - * ttm_bo_list_ref_sub - * - * @bo: The buffer object. - * @count: The number of references with which to decrease @bo::list_kref; - * @never_free: The refcount should not reach zero with this operation. - * - * Release @count lru list references to this buffer object. - */ -extern void ttm_bo_list_ref_sub(struct ttm_buffer_object *bo, int count, - bool never_free); - /** * ttm_bo_add_to_lru * @@ -367,7 +354,7 @@ extern void ttm_bo_add_to_lru(struct ttm_buffer_object *bo); * and is usually called just immediately after the bo has been reserved to * avoid recursive reservation from lru lists. */ -extern int ttm_bo_del_from_lru(struct ttm_buffer_object *bo); +extern void ttm_bo_del_from_lru(struct ttm_buffer_object *bo); /** * ttm_bo_move_to_lru_tail diff --git a/include/linux/kref.h b/include/linux/kref.h index e2df6d3..ad8050a 100644 --- a/include/linux/kref.h +++ b/include/linux/kref.h @@ -52,9 +52,8 @@ static inline void kref_get(struct kref *kref) } /** - * kref_sub - subtract a number of refcounts for object. + * kref_put - decrement refcount for object. * @kref: object. - * @count: Number of recounts to subtract. * @release: pointer to the function that will clean up the object when the * last reference to the object is released. * This pointer is required, and it is not acceptable to pass kfree @@ -63,46 +62,23 @@ static inline void kref_get(struct kref *kref) * maintainer, and anyone else who happens to notice it. You have * been warned. * - * Subtract @count from the refcount, and if 0, call release(). + * Decrement the refcount, and if 0, call release(). * Return 1 if the object was removed, otherwise return 0. Beware, if this * function returns 0, you still can not count on the kref from remaining in * memory. Only use the return value if you want to see if the kref is now * gone, not present. */ -static inline int kref_sub(struct kref *kref, unsigned int count, - void (*release)(struct kref *kref)) +static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)) { WARN_ON(release == NULL); - if (atomic_sub_and_test((int) count, &kref->refcount)) { + if (atomic_dec_and_test(&kref->refcount)) { release(kref); return 1; } return 0; } -/** - * kref_put - decrement refcount for object. - * @kref: object. - * @release: pointer to the function that will clean up the object when the - * last reference to the object is released. - * This pointer is required, and it is not acceptable to pass kfree - * in as this function. If the caller does pass kfree to this - * function, you will be publicly mocked mercilessly by the kref - * maintainer, and anyone else who happens to notice it. You have - * been warned. - * - * Decrement the refcount, and if 0, call release(). - * Return 1 if the object was removed, otherwise return 0. Beware, if this - * function returns 0, you still can not count on the kref from remaining in - * memory. Only use the return value if you want to see if the kref is now - * gone, not present. - */ -static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)) -{ - return kref_sub(kref, 1, release); -} - static inline int kref_put_mutex(struct kref *kref, void (*release)(struct kref *kref), struct mutex *lock)