Commit 2cd648c1 authored Jul 12, 2017 by Manfred Spraul Committed by Linus Torvalds Jul 12, 2017

include/linux/sem.h: correctly document sem_ctime

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.

Link: http://lkml.kernel.org/r/20170515171912.6298-4-manfred@colorfullife.com


Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: <1vier1@web.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent dba4cdd3

include/linux/sem.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */

include/uapi/linux/sem.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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 */