Date: Thu, 27 Sep 2012 07:58:43 -0400 From: John Baldwin <jhb@freebsd.org> To: Ryan Stone <rysto32@gmail.com> Cc: freebsd-net@freebsd.org, Jack Vogel <jfvogel@gmail.com>, Vijay Singh <vijju.singh@gmail.com> Subject: Re: ixgbe rx & tx locks Message-ID: <201209270758.43445.jhb@freebsd.org> In-Reply-To: <CAFMmRNxxZRUb9Y9WizUW3KrfKuxT11D7=q3KEBdazGfsqku6Ow@mail.gmail.com> References: <CALCNsJSSQSWV7vNVR-Sn8CPDKbUBBLpSH0b-HYMJo3SXvkOY=w@mail.gmail.com> <201209261538.11588.jhb@freebsd.org> <CAFMmRNxxZRUb9Y9WizUW3KrfKuxT11D7=q3KEBdazGfsqku6Ow@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wednesday, September 26, 2012 5:28:09 pm Ryan Stone wrote: > On Wed, Sep 26, 2012 at 3:38 PM, John Baldwin <jhb@freebsd.org> wrote: > >> ix:rx -> udp -> udpinp -> in_multi_mtx -> ix:core -> ix:rx > > > > Hmm, I'm not sure where the 'in_multi_mtx -> ix:core' bit comes from. > > I think that is the broken part of this. The SIOCADDMULTI and SIOCDELMULTI > > ioctls are invoked without any stack locks held, so it shouldn't come from > > there. > > I gave the backtrace for this part. in_joingroup_locked is called > with the in_multi_mtx held, which calls if_addmulti, which calls the > ioctl handler. My bad. Too many locks. :( We do drop the IF_ADDR_LOCK when calling if_ioctl from if_addmulti(), but you are correct, in_multi_mtx is held. Not sure how resolvable that is. Many drivers need to do a fair bit of work in SIOCADDMULTI/SIOCDELMUTLI (that is, reprogram the entire multicast table). One alternative might be to use a separate lock just for the MAC filters. That might break the in_multi_mtx -> ix:core order by letting you avoid grabbing ix:core for those ioctls. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201209270758.43445.jhb>