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Date: Sun, 25 May 2014 20:21:03 +0200 From: Manfred Spraul <manfred@...orfullife.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: LKML <linux-kernel@...r.kernel.org>, Davidlohr Bueso <davidlohr.bueso@...com>, Michael Kerrisk <mtk.manpages@...il.com>, 1vier1@....de, Manfred Spraul <manfred@...orfullife.com> Subject: [PATCH 7/6] 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 printk_once() that is triggered if a thread hits the relevant case. Signed-off-by: Manfred Spraul <manfred@...orfullife.com> Cc: Davidlohr Bueso <davidlohr.bueso@...com> Cc: Michael Kerrisk <mtk.manpages@...il.com> --- ipc/sem.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/ipc/sem.c b/ipc/sem.c index 9106321..3cc2f7b6 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1000,6 +1000,18 @@ static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q, { 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. + */ + printk_once(KERN_INFO "semctl(GETNCNT/GETZCNT) is since 3.16 Single " \ + "Unix Specification compliant.\n" \ + "The task %d triggered the difference, " \ + "watch for misbehavior.", current->pid); + if (sop->sem_num != semnum) return 0; -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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