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

de2657f9 · Rik van Riel <[email protected]> · 2013-05-09 16:59:59 -04:00

The semctl GETNCNT returns the number of semops waiting for the
specified semaphore to become nonzero.  After commit 9f1bc2c9022c
("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 <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: de2657f94acd4f0df44626db7c4d2b71babc8cd3
Parents: ebc2e5e6

Changes

1 files changed · +7 −0

File	Status	Add	Del	Content
ipc/sem.c	modified	+7	−0	View file

ipc/sem.c

View file

diff --git a/ipc/sem.c b/ipc/sem.c
index 04b264d..a7e40ed 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -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;