Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Manfred Spraul <manfred@colorfullife.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Davidlohr Bueso <dave@stgolabs.net>,
        Dmitry Vyukov <dvyukov@google.com>
Cc:     LKML <linux-kernel@vger.kernel.org>, 1vier1@web.de,
        Kees Cook <keescook@chromium.org>,
        Manfred Spraul <manfred@colorfullife.com>
Subject: [PATCH 05/12] ipc/util.c: correct comment in ipc_obtain_object_check
Date:   Thu, 12 Jul 2018 20:52:34 +0200
Message-Id: <20180712185241.4017-6-manfred@colorfullife.com>
In-Reply-To: <20180712185241.4017-1-manfred@colorfullife.com>
References: <20180712185241.4017-1-manfred@colorfullife.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The comment that explains ipc_obtain_object_check is wrong:
The function checks the sequence number, not the reference
counter.
Note that checking the reference counter would be meaningless:
The reference counter is decreased without holding any locks,
thus an object with kern_ipc_perm.deleted=true may disappear at
the end of the next rcu grace period.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
---
 ipc/util.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ipc/util.c b/ipc/util.c
index cffd12240f67..5cc37066e659 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -628,8 +628,8 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
  * @ids: ipc identifier set
  * @id: ipc id to look for
  *
- * Similar to ipc_obtain_object_idr() but also checks
- * the ipc object reference counter.
+ * Similar to ipc_obtain_object_idr() but also checks the ipc object
+ * sequence number.
  *
  * Call inside the RCU critical section.
  * The ipc object is *not* locked on exit.
-- 
2.17.1