Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree

Cyrill Gorcunov
2012-04-10T22:54:38Z

On Mon, Apr 09, 2012 at 08:25:22PM -0700, Eric W. Biederman wrote:
...
>
> Having just read through it again the only possible issue I can see is
> that we compare file descriptors after dropping all of the locks.
>
> Since rcu_read_lock doesn't participate in ABBA deadlocks. My gut feel
> is that we should hold rcu_read_lock across the hole file pointer
> comparison to remove the possibility of races as file descriptor
> pointers go away.
>
> Still in practice I don't think it matters. At worst there is the
> slightest possibility of returning a value instead of -EBADF. The
> expectation is for all of the tasks we are operating on to be frozen,
> and even if the tasks are not frozen it is a very tiny window for a race
> to be in.

yeah, we use this call heavily on stopped tasks atm

> > So what do people think? Any issues? Any nacks? Should I sneak it
> > into Linus this week or do we need to go another round with it all?
>
> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>

Thanks a lot, Eric!

Cyrill