Commit 1994862d authored Jun 06, 2014 by Manfred Spraul Committed by Linus Torvalds Jun 06, 2014

ipc/sem.c: bugfix for semctl(,,GETZCNT)



GETZCNT is supposed to return the number of threads that wait until a
semaphore value becomes 0.

The current implementation overlooks complex operations that contain
both wait-for-zero operation and operations that alter at least one
semaphore.

The patch fixes that.  It's intentionally copy&paste, this will be
cleaned up in the next patch.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4bb6657d

ipc/sem.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -1047,6 +1047,16 @@ static int count_semzcnt(struct sem_array *sma, ushort semnum)
		&& !(sops[i].sem_flg & IPC_NOWAIT))
		semzcnt++;
		}
		list_for_each_entry(q, &sma->pending_alter, list) {
		struct sembuf *sops = q->sops;
		int nsops = q->nsops;
		int i;
		for (i = 0; i < nsops; i++)
		if (sops[i].sem_num == semnum
		&& (sops[i].sem_op == 0)
		&& !(sops[i].sem_flg & IPC_NOWAIT))
		semzcnt++;
		}
		return semzcnt;
		}

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