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mISDN: fix misdn_add_timer()/misdn_del_timer() race 

do add_timer() *before* unlocking dev->lock, or unpleasant things can
happen if misdn_del_timer() on another CPU finds the sucker, calls
del_timer_sync() (which does nothing, since we hadn't started the
timer yet) and frees it, just as we get around to add_timer()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2013-04-15 17:04:04 -04:00
parent 1b1089561c
commit 1678ec00a6
1 changed files with 5 additions and 9 deletions
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14
drivers/isdn/mISDN/timerdev.c
View File

@ -173,7 +173,6 @@ static int
misdn_add_timer(struct mISDNtimerdev *dev, int timeout)
{
int id;
u_long flags;
struct mISDNtimer *timer;
if (!timeout) {
@ -184,19 +183,16 @@ misdn_add_timer(struct mISDNtimerdev *dev, int timeout)
timer = kzalloc(sizeof(struct mISDNtimer), GFP_KERNEL);
if (!timer)
return -ENOMEM;
spin_lock_irqsave(&dev->lock, flags);
timer->id = dev->next_id++;
timer->dev = dev;
setup_timer(&timer->tl, dev_expire_timer, (long)timer);
spin_lock_irq(&dev->lock);
id = timer->id = dev->next_id++;
if (dev->next_id < 0)
dev->next_id = 1;
list_add_tail(&timer->list, &dev->pending);
spin_unlock_irqrestore(&dev->lock, flags);
timer->dev = dev;
timer->tl.data = (long)timer;
timer->tl.function = dev_expire_timer;
init_timer(&timer->tl);
timer->tl.expires = jiffies + ((HZ * (u_long)timeout) / 1000);
add_timer(&timer->tl);
id = timer->id;
spin_unlock_irq(&dev->lock);
}
return id;
}