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Commit 1994862d authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds
Browse files

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: default avatarManfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus 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;

}