Commit de2657f9 authored May 09, 2013 by Rik van Riel Committed by Linus Torvalds May 09, 2013

ipc,sem: fix semctl(..., GETNCNT)



The semctl GETNCNT returns the number of semops waiting for the
specified semaphore to become nonzero.  After commit 9f1bc2c9
("ipc,sem: have only one list in struct sem_queue"), the semops waiting
on just one semaphore are waiting on that semaphore's list.

In order to return the correct count, we have to walk that list too, in
addition to the sem_array's list for complex operations.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ebc2e5e6

ipc/sem.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -796,6 +796,13 @@ static int count_semncnt (struct sem_array * sma, ushort semnum)
		struct sem_queue * q;

		semncnt = 0;
		list_for_each_entry(q, &sma->sem_base[semnum].sem_pending, list) {
		struct sembuf * sops = q->sops;
		BUG_ON(sops->sem_num != semnum);
		if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT))
		semncnt++;
		}

		list_for_each_entry(q, &sma->sem_pending, list) {
		struct sembuf * sops = q->sops;
		int nsops = q->nsops;

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