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From: Manfred Spraul <manfred@colorfullife.com>
To: mtk.manpages@gmail.com, Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	1vier1@web.de, Davidlohr Bueso <dave@stgolabs.net>,
	mingo@kernel.org, peterz@infradead.org, fabf@skynet.be,
	Manfred Spraul <manfred@colorfullife.com>,
	linux-man@vger.kernel.org
Subject: [PATCH 03/20] include/linux/sem.h: Correctly document sem_ctime
Date: Thu, 25 May 2017 20:50:50 +0200	[thread overview]
Message-ID: <20170525185107.12869-4-manfred@colorfullife.com> (raw)
In-Reply-To: <20170525185107.12869-1-manfred@colorfullife.com>

sem_ctime is initialized to the semget() time and then updated at every
semctl() that changes the array.
Thus it does not represent the time of the last change.

Especially, semop() calls are only stored in sem_otime, not in sem_ctime.

This is already described in ipc/sem.c, I just overlooked that there is
a comment in include/linux/sem.h and man semctl(2) as well.

So: Correct wrong comments.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: linux-man@vger.kernel.org
---
 include/linux/sem.h      | 2 +-
 include/uapi/linux/sem.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/sem.h b/include/linux/sem.h
index 9db1409..be5cf2e 100644
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -30,7 +30,7 @@ struct sem {
 /* One sem_array data structure for each set of semaphores in the system. */
 struct sem_array {
 	struct kern_ipc_perm	sem_perm;	/* permissions .. see ipc.h */
-	time_t			sem_ctime;	/* last change time */
+	time_t			sem_ctime;	/* create/last semctl() time */
 	struct list_head	pending_alter;	/* pending operations */
 						/* that alter the array */
 	struct list_head	pending_const;	/* pending complex operations */
diff --git a/include/uapi/linux/sem.h b/include/uapi/linux/sem.h
index dd73b90..67eb903 100644
--- a/include/uapi/linux/sem.h
+++ b/include/uapi/linux/sem.h
@@ -23,7 +23,7 @@
 struct semid_ds {
 	struct ipc_perm	sem_perm;		/* permissions .. see ipc.h */
 	__kernel_time_t	sem_otime;		/* last semop time */
-	__kernel_time_t	sem_ctime;		/* last change time */
+	__kernel_time_t	sem_ctime;		/* create/last semctl() time */
 	struct sem	*sem_base;		/* ptr to first semaphore in array */
 	struct sem_queue *sem_pending;		/* pending operations to be processed */
 	struct sem_queue **sem_pending_last;	/* last pending operation */
-- 
2.9.3

  parent reply	other threads:[~2017-05-25 18:55 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-08 22:23 [PATCH] ipc/sem: Avoid indexing past end of sem_array Kees Cook
2017-05-14 13:54 ` Manfred Spraul
2017-05-15 17:40   ` Kees Cook
2017-05-15 17:19 ` [PATCH 0/2] Misc cleanups for ipc Manfred Spraul
2017-05-15 17:19   ` [PATCH 1/3] ipc/sem.c: remove sem_base, embed struct sem Manfred Spraul
2017-05-15 20:08     ` Andrew Morton
2017-05-15 22:16       ` Kees Cook
2017-05-16  5:46     ` Christoph Hellwig
2017-05-15 17:19   ` [PATCH 2/3] ipc: merge ipc_rcu and kern_ipc_perm Manfred Spraul
2017-05-16  0:03     ` Kees Cook
2017-05-15 17:19   ` [PATCH 3/3] include/linux/sem.h: Correctly document sem_ctime Manfred Spraul
2017-05-25 18:50 ` [PATCH 0/20 V3] Misc cleanups for ipc Manfred Spraul
2017-05-25 18:50   ` [PATCH 01/20] ipc/sem.c: remove sem_base, embed struct sem Manfred Spraul
2017-05-25 19:43     ` Kees Cook
2017-05-25 18:50   ` [PATCH 02/20] ipc: merge ipc_rcu and kern_ipc_perm Manfred Spraul
2017-05-25 19:34     ` Kees Cook
2017-05-26  3:37       ` Kees Cook
2017-05-25 18:50   ` Manfred Spraul [this message]
2017-05-25 18:50   ` [PATCH 04/20] ipc: Drop non-RCU allocation Manfred Spraul
2017-05-25 19:35     ` Kees Cook
2017-05-25 18:50   ` [PATCH 05/20] ipc/sem: Do not use ipc_rcu_free() Manfred Spraul
2017-05-25 18:50   ` [PATCH 06/20] ipc/shm: " Manfred Spraul
2017-05-25 18:50   ` [PATCH 07/20] ipc/msg: " Manfred Spraul
2017-05-25 18:50   ` [PATCH 08/20] ipc/util: Drop ipc_rcu_free() Manfred Spraul
2017-05-25 18:50   ` [PATCH 09/20] ipc/sem: Avoid ipc_rcu_alloc() Manfred Spraul
2017-05-25 18:50   ` [PATCH 10/20] ipc/shm: " Manfred Spraul
2017-05-25 18:50   ` [PATCH 11/20] ipc/msg: " Manfred Spraul
2017-05-25 18:50   ` [PATCH 12/20] ipc/util: Drop ipc_rcu_alloc() Manfred Spraul
2017-05-25 18:51   ` [PATCH 13/20] ipc/sem.c: Avoid ipc_rcu_putref for failed ipc_addid() Manfred Spraul
2017-05-25 18:51   ` [PATCH 14/20] ipc/shm.c: " Manfred Spraul
2017-05-25 18:51   ` [PATCH 15/20] ipc/msg.c: " Manfred Spraul
2017-05-25 18:51   ` [PATCH 16/20] ipc: Move atomic_set() to where it is needed Manfred Spraul
2017-05-25 18:51   ` [PATCH 17/20] ipc/shm: Remove special shm_alloc/free Manfred Spraul
2017-05-25 18:51   ` [PATCH 18/20] ipc/msg: Remove special msg_alloc/free Manfred Spraul
2017-05-25 18:51   ` [PATCH 19/20] ipc/sem: Drop __sem_free() Manfred Spraul
2017-05-25 18:51   ` [PATCH 20/20] ipc/util.h: Update documentation for ipc_getref() and ipc_putref() Manfred Spraul
2017-05-25 19:45   ` [PATCH 0/20 V3] Misc cleanups for ipc Kees Cook
2017-05-26  1:56     ` Manfred Spraul

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