On Sun, 2013-09-22 at 10:17 +0200, Mike Galbraith wrote:
> On Sun, 2013-09-22 at 10:11 +0800, Jia He wrote:
> > In commit 0a2b9d4c,the update of semaphore's sem_otime(last semop time)
> > was removed because he wanted to move setting sem->sem_otime to one
> > place. But after that, the initial semop() will not set the otime
> > because its sem_op value is 0(in semtimedop,will not change
> > otime if alter == 1).
> >
> > the error case:
> > process_a(server) process_b(client)
> > semget()
> > semctl(SETVAL)
> > semop()
> > semget()
> > setctl(IP_STAT)
> > for(;;) { <--not successful here
> > check until sem_otime > 0
> > }
>
> Why not..
(pokes evolution's don't-munge-me button)
ipc,sem: Create semaphores with plausible sem_otime.
Signed-off-by: Mike Galbraith <bitbuc...@online.de>
diff --git a/ipc/sem.c b/ipc/sem.c
index 4108889..f2564d7 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -471,19 +471,20 @@ static int newary(struct ipc_namespace *ns, struct
ipc_params *params)
ns->used_sems += nsems;
sma->sem_base = (struct sem *) &sma[1];
+ sma->complex_count = 0;
+ INIT_LIST_HEAD(&sma->pending_alter);
+ INIT_LIST_HEAD(&sma->pending_const);
+ INIT_LIST_HEAD(&sma->list_id);
+ sma->sem_nsems = nsems;
+ sma->sem_ctime = get_seconds();
for (i = 0; i < nsems; i++) {
INIT_LIST_HEAD(&sma->sem_base[i].pending_alter);
INIT_LIST_HEAD(&sma->sem_base[i].pending_const);
spin_lock_init(&sma->sem_base[i].lock);
+ sma->sem_base[i].sem_otime = sma->sem_ctime;
}
- sma->complex_count = 0;
- INIT_LIST_HEAD(&sma->pending_alter);
- INIT_LIST_HEAD(&sma->pending_const);
- INIT_LIST_HEAD(&sma->list_id);
- sma->sem_nsems = nsems;
- sma->sem_ctime = get_seconds();
sem_unlock(sma, -1);
rcu_read_unlock();
--
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