Am Freitag, 2. August 2002 19:37 schrieb Dave Hansen:
> Oliver Neukum wrote:
> > Am Freitag, 2. August 2002 15:46 schrieb Kasper Dupont:
> >>Is there a race condition in this piece of code from do_fork in
> >
> > It would seem so. Perhaps the BKL was taken previously.
>
> Even if it was, I doubt the code ever knowingly relied upon it. If I
> know that I'm protected under a lock, I rarely go to the trouble of
> atomic operations.
That depends on where else you need these variables.
> The root of the problem is that the reference count is being relied on
> for the wrong thing. There is a race on p->user between the
> dup_task_struct() and whenever the atomic_inc(&p->user->__count)
> occcurs. The user reference count needs to be incremented in
> dup_task_struct(), before the copy occurs.
I don't get you. The user_struct can hardly go away while we are
forking.
IMHO you should add a spinlock to user_struct and take it.
A clear solution that doesn't hurt the common case.
Regards
Oliver
-
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/
This archive was generated by hypermail 2b29 : Wed Aug 07 2002 - 22:00:20 EST