Date: Tue, 16 Oct 2012 16:12:01 +0400 From: "Alexander V. Chernikov" <melifaro@FreeBSD.org> To: Ryan Stone <rysto32@gmail.com> Cc: Jack Vogel <jfvogel@gmail.com>, net@freebsd.org Subject: Re: ixgbe & if_igb RX ring locking Message-ID: <507D4F11.2030704@FreeBSD.org> In-Reply-To: <CAFMmRNxT=GWxc6r7B81ENjzwJmfea3016Sh-DxJEGBwybM0QwQ@mail.gmail.com> References: <5079A9A1.4070403@FreeBSD.org> <20121015162926.GV89655@FreeBSD.org> <CAFMmRNxT=GWxc6r7B81ENjzwJmfea3016Sh-DxJEGBwybM0QwQ@mail.gmail.com>
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On 16.10.2012 00:48, Ryan Stone wrote: > On Mon, Oct 15, 2012 at 12:29 PM, Gleb Smirnoff <glebius@freebsd.org> wrote: >> To me this unlock/lock looks like a legacy from times, when the driver >> had a single mutex for both TX and RX parts. >> >> And removing this re-locking in foo_rxeof() was one of the aims for separate >> TX/RX locking. >> >> Really, lurking through history shows that once driver had split its locking >> to separate RX and TX part, these unlock/lock was removed. However, later >> this unlock/lock was added back: >> >> http://svnweb.freebsd.org/base/head/sys/dev/e1000/if_igb.c?revision=209068&view=markup >> >> , without any comments for the reason it is added back. > > There's a convoluted LOR if you call into the stack with the RX lock > held which is described here: > > http://lists.freebsd.org/pipermail/freebsd-net/2012-September/033371.html Are you using stock ixgbe driver? lock order reversal:^M^M 1st 0xffffff800153c138 ix:rx (ix:rx) @ src/sys/dev/ixgbe/ixgbe.c:7113^M^M 2nd 0xffffffff80af9c48 udp (udp) @ src/sys/netinet/udp_usrreq.c:471^M^M It seems to me than ixgbe.c was always like ~5.5k lines of code, line 7113 seems a bit suspicious. 2nd 0xffffff8001539400 ixgbe0 (IXGBE Core Lock) @ src/sys/dev/ixgbe/ixgbe.c:1725 Nearest IXGBE_CORE_LOCK() in r217917 (8.2-R) resides at line 905. Maybe I'm missing something obvious? > -- WBR, Alexander
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