Subject: Re: [IPV4 3/5] fib_trie: dump doesnt use RCU

From: David Miller <[email-masked]>
Date: Wed, 23 Jan 2008 22:43:37 -0800 (PST)

From: Patrick McHardy <[email-masked]>
Date: Thu, 24 Jan 2008 07:41:08 +0100

> David Miller wrote:
> > and nothing in that code path retakes the RTNL semaphore.
> 
> Actually we're always holding the rtnl during dumps, nlk->cb_mutex points
> to rtnl_mutex in case of rtnetlink. It used to be held only during the first
> ->dump invocation and not on continuations, but I changed this a few 
> versions ago.

My bad.  Thanks for the correction Patrick.

But continuations can occur on subsequent recvmsg() calls,
does it return to userspace with the mutex held?  If so
I'm pretty sure that's not allowed.