Subject: [merged] ipc-semc-add-a-printk_once-for-semctlgetncnt-getzcnt.patch removed from -mm tree To: manfred@xxxxxxxxxxxxxxxx,davidlohr@xxxxxx,joe@xxxxxxxxxxx,mtk.manpages@xxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Mon, 09 Jun 2014 12:38:18 -0700 The patch titled Subject: ipc/sem.c: add a printk_once for semctl(GETNCNT/GETZCNT) has been removed from the -mm tree. Its filename was ipc-semc-add-a-printk_once-for-semctlgetncnt-getzcnt.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Subject: ipc/sem.c: add a printk_once for semctl(GETNCNT/GETZCNT) The actual Linux implementation for semctl(GETNCNT) and semctl(GETZCNT) always (since 0.99.10) reported a thread as sleeping on all semaphores that are listed in the semop() call. The documented behavior (both in the Linux man page and in the Single Unix Specification) is that a task should be reported on exactly one semaphore: The semaphore that caused the thread to got to sleep. This patch adds a pr_info_once() that is triggered if a thread hits the relevant case. The code triggers slightly too often, otherwise it would be necessary to replicate the old code. As there are no known users of GETNCNT or GETZCNT, this is done to prevent unnecessary bloat. The task that triggered is reported with name (tsk->comm) and pid. Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Acked-by: Davidlohr Bueso <davidlohr@xxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/sem.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff -puN ipc/sem.c~ipc-semc-add-a-printk_once-for-semctlgetncnt-getzcnt ipc/sem.c --- a/ipc/sem.c~ipc-semc-add-a-printk_once-for-semctlgetncnt-getzcnt +++ a/ipc/sem.c @@ -1000,6 +1000,17 @@ static int check_qop(struct sem_array *s { struct sembuf *sop = q->blocking; + /* + * Linux always (since 0.99.10) reported a task as sleeping on all + * semaphores. This violates SUS, therefore it was changed to the + * standard compliant behavior. + * Give the administrators a chance to notice that an application + * might misbehave because it relies on the Linux behavior. + */ + pr_info_once("semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant.\n" + "The task %s (%d) triggered the difference, watch for misbehavior.\n", + current->comm, task_pid_nr(current)); + if (sop->sem_num != semnum) return 0; _ Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are origin.patch slab-leaks3-default-y.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html