Re: [RFC] Race condition?

From: Dave Hansen (
Date: Fri Aug 02 2002 - 12:37:22 EST

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.

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.

Dave Hansen

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