On Tue, Dec 20, 2016 at 05:37:20PM +0000, Alexander Bluhm wrote:
> Obviosly a NET_LOCK() is missing in tcp_sysctl().
> I think it is better to place the lock into net_sysctl() where all
> the protocol sysctls are called via pr_sysctl.  Then we don't have
> to decide each case individually.  As calling sysctl(2) is in the
> slow path, doing fine grained locking has no benefit.  Many sysctl
> cases copy out a struct.  Having a lock around that keeps the struct
> consistent.

Holding locks across copyout/copyin is always fishy.

In this particular case, what happens if the access results in a page
fault and the area comes from a nfs mapped file? If network i/o is done
from the same context, this should result in 'locking against myself'
assertion failure.

That said, I'm not exactly familiar with the area, so maybe that's a
false alarm.

Mateusz Guzik <mjguzik gmail.com>

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