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 <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Michael Kerrisk <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Jun 6, 2014 · 1994862 · 1994862
1 parent 4bb6657
commit 1994862
Showing 1 changed file with 10 additions and 0 deletions.
diff --git a/ipc/sem.c b/ipc/sem.c
@@ -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;
 }