Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753163AbdF0Lli (ORCPT ); Tue, 27 Jun 2017 07:41:38 -0400 Received: from mga03.intel.com ([134.134.136.65]:26052 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753023AbdF0Lkz (ORCPT ); Tue, 27 Jun 2017 07:40:55 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,399,1493708400"; d="scan'208";a="872136664" From: Elena Reshetova To: axboe@kernel.dk Cc: james.bottomley@hansenpartnership.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-btrfs@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, keescook@chromium.org, fujita.tomonori@lab.ntt.co.jp, mingo@redhat.com, clm@fb.com, jbacik@fb.com, dsterba@suse.com, Elena Reshetova , Hans Liljestrand , David Windsor Subject: [PATCH 3/5] block: convert blkcg_gq.refcnt from atomic_t to refcount_t Date: Tue, 27 Jun 2017 14:39:58 +0300 Message-Id: <1498563601-10949-4-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1498563601-10949-1-git-send-email-elena.reshetova@intel.com> References: <1498563601-10949-1-git-send-email-elena.reshetova@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2317 Lines: 71 refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor --- block/blk-cgroup.c | 2 +- include/linux/blk-cgroup.h | 9 ++++----- 2 files changed, 5 insertions(+), 6 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 0480892..3762908 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -107,7 +107,7 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, blkg->q = q; INIT_LIST_HEAD(&blkg->q_node); blkg->blkcg = blkcg; - atomic_set(&blkg->refcnt, 1); + refcount_set(&blkg->refcnt, 1); /* root blkg uses @q->root_rl, init rl only for !root blkgs */ if (blkcg != &blkcg_root) { diff --git a/include/linux/blk-cgroup.h b/include/linux/blk-cgroup.h index 01b62e7..e54f048 100644 --- a/include/linux/blk-cgroup.h +++ b/include/linux/blk-cgroup.h @@ -19,6 +19,7 @@ #include #include #include +#include /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */ #define BLKG_STAT_CPU_BATCH (INT_MAX / 2) @@ -122,7 +123,7 @@ struct blkcg_gq { struct request_list rl; /* reference count */ - atomic_t refcnt; + refcount_t refcnt; /* is this blkg online? protected by both blkcg and q locks */ bool online; @@ -354,8 +355,7 @@ static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) */ static inline void blkg_get(struct blkcg_gq *blkg) { - WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0); - atomic_inc(&blkg->refcnt); + refcount_inc(&blkg->refcnt); } void __blkg_release_rcu(struct rcu_head *rcu); @@ -366,8 +366,7 @@ void __blkg_release_rcu(struct rcu_head *rcu); */ static inline void blkg_put(struct blkcg_gq *blkg) { - WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0); - if (atomic_dec_and_test(&blkg->refcnt)) + if (refcount_dec_and_test(&blkg->refcnt)) call_rcu(&blkg->rcu_head, __blkg_release_rcu); } -- 2.7.4