aboutsummaryrefslogtreecommitdiff
path: root/ipc
diff options
context:
space:
mode:
authorManfred Spraul <manfred@colorfullife.com>2013-05-26 11:08:52 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-26 15:14:51 -0700
commitab465df9dda42a997f7537c875127eeb6a88158c (patch)
tree28a1ec28c15f1b59c938b7757c8f56eed0de0ecd /ipc
parent89ff77837a67994e4a4a20bb648687fbcc3083f2 (diff)
downloadlinaro-lsk-ab465df9dda42a997f7537c875127eeb6a88158c.tar.gz
ipc/sem.c: Fix missing wakeups in do_smart_update_queue()
do_smart_update_queue() is called when an operation (semop, semctl(SETVAL), semctl(SETALL), ...) modified the array. It must check which of the sleeping tasks can proceed. do_smart_update_queue() missed a few wakeups: - if a sleeping complex op was completed, then all per-semaphore queues must be scanned - not only those that were modified by *sops - if a sleeping simple op proceeded, then the global queue must be scanned again And: - the test for "|sops == NULL) before scanning the global queue is not required: If the global queue is empty, then it doesn't need to be scanned - regardless of the reason for calling do_smart_update_queue() The patch is not optimized, i.e. even completing a wait-for-zero operation causes a rescan. This is done to keep the patch as simple as possible. Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/sem.c27
1 files changed, 22 insertions, 5 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index a7e40ed8a07..70480a3aa69 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -752,19 +752,29 @@ static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsop
int otime, struct list_head *pt)
{
int i;
+ int progress;
- if (sma->complex_count || sops == NULL) {
- if (update_queue(sma, -1, pt))
+ progress = 1;
+retry_global:
+ if (sma->complex_count) {
+ if (update_queue(sma, -1, pt)) {
+ progress = 1;
otime = 1;
+ sops = NULL;
+ }
}
+ if (!progress)
+ goto done;
if (!sops) {
/* No semops; something special is going on. */
for (i = 0; i < sma->sem_nsems; i++) {
- if (update_queue(sma, i, pt))
+ if (update_queue(sma, i, pt)) {
otime = 1;
+ progress = 1;
+ }
}
- goto done;
+ goto done_checkretry;
}
/* Check the semaphores that were modified. */
@@ -772,8 +782,15 @@ static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsop
if (sops[i].sem_op > 0 ||
(sops[i].sem_op < 0 &&
sma->sem_base[sops[i].sem_num].semval == 0))
- if (update_queue(sma, sops[i].sem_num, pt))
+ if (update_queue(sma, sops[i].sem_num, pt)) {
otime = 1;
+ progress = 1;
+ }
+ }
+done_checkretry:
+ if (progress) {
+ progress = 0;
+ goto retry_global;
}
done:
if (otime)