svn commit: r233199 - in stable/8/sys: i386/conf netinet6
jhb at freebsd.org
Tue Mar 20 19:04:01 UTC 2012
On Tuesday, March 20, 2012 5:02:48 am Sergey Kandaurov wrote:
> On 20 March 2012 00:15, John Baldwin <jhb at freebsd.org> wrote:
> > Author: jhb
> > Date: Mon Mar 19 20:15:18 2012
> > New Revision: 233199
> > URL: http://svn.freebsd.org/changeset/base/233199
> > Log:
> > MFC 225096:
> > Fix if_addr_mtx recursion in mld6.
> Ehh.. Thank you for doing this.
> As I mentioned earlier I could not reproduce this problem myself
> in RELENG_8, that's why it was not MFCed so far...
To be honest, my main movitation was to remove a merge conflict in my
subsequent MFC of the IF_ADDR locking changes. I could have patched
the locking in the old mld6.c, but when I reviewed your diff, I figured
it would be better to merge it first instead.
> > mld_set_version() is called only from mld_v1_input_query() and
> > mld_v2_input_query() both holding the if_addr_mtx lock, and then calling
> > into mld_v2_cancel_link_timers() acquires it the second time, which results
> > in mtx recursion. To avoid that, delay if_addr_mtx acquisition until after
> > mld_set_version() is called; while here, further reduce locking scope
> > to protect only the needed pieces: if_multiaddrs, in6m_lookup_locked().
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