Messages in this thread | | | Date | Sat, 28 Jan 2006 23:41:27 -0600 | From | Hareesh Nagarajan <> | Subject | Potentially racy del_timer(&timer); ... ; add_timer(&timer) sequence |
| |
I was going through the kernel sources looking for places where the following sequence occurs:
del_timer(&timer); ... modify timer ... add_timer(&timer)
To my surprise, I found numerous place where such code appears. I figured this kind of code will always be (potentially) racy on SMP machines.
Examples are: 1. net/lapb/lapb_timer.c
void lapb_start_t1timer(struct lapb_cb *lapb) { del_timer(&lapb->t1timer);
lapb->t1timer.data = (unsigned long)lapb; lapb->t1timer.function = &lapb_t1timer_expiry; lapb->t1timer.expires = jiffies + lapb->t1;
add_timer(&lapb->t1timer); }
mod_timer could have been used.
2. arch/i386/mach-voyager/voyager_thread.c 3. kernel/acct.c
del_timer(&acct_globals.timer); acct_globals.needcheck = 0; acct_globals.timer.expires = jiffies + ACCT_TIMEOUT*HZ; add_timer(&acct_globals.timer);
Would anyone on LKML interested in getting this cleaned up? I could do it, if it would be useful. Or perhaps someone on Kernel Janitors is already working on it.
Thanks,
Hareesh Nagarajan www.cs.uic.edu/~hnagaraj - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |