Date: Thu, 20 Oct 2016 13:48:29 +0000 (UTC) From: Andrew Gallatin <gallatin@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r307673 - head/sys/net Message-ID: <201610201348.u9KDmTpE022296@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: gallatin Date: Thu Oct 20 13:48:29 2016 New Revision: 307673 URL: https://svnweb.freebsd.org/changeset/base/307673 Log: Clear mbuf hashtype on loopback when RSS is enabled. The hashtype on an outgoing mbuf reflects the correct hash on the transmit side of the connection. If this hash persists on loopback, the receiving RSS/PCBGROUP code will use it to look up the pcbgroup for the transmit side, which will often not match the pcbgroup for the receive side of the connection. This leads to TCP connections hanging, and dropping the SYN/ACK packet. This is essentially the same as having a hardware network card generate mbufs with an incorrect RSS hash. There are a number of places which can set the hash on transmit, so the simplest fix is to simply clear the hash at loopback time. Clearing the hash allows a new, correct hash to be calculated in software on the receive side. Reviewed by: jtl Discussed with: adrian Sponsored by: Netflix Modified: head/sys/net/if_loop.c Modified: head/sys/net/if_loop.c ============================================================================== --- head/sys/net/if_loop.c Thu Oct 20 13:12:19 2016 (r307672) +++ head/sys/net/if_loop.c Thu Oct 20 13:48:29 2016 (r307673) @@ -36,6 +36,7 @@ #include "opt_inet.h" #include "opt_inet6.h" +#include "opt_rss.h" #include <sys/param.h> #include <sys/systm.h> @@ -224,6 +225,10 @@ looutput(struct ifnet *ifp, struct mbuf if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1); if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len); +#ifdef RSS + M_HASHTYPE_CLEAR(m); +#endif + /* BPF writes need to be handled specially. */ if (dst->sa_family == AF_UNSPEC || dst->sa_family == pseudo_AF_HDRCMPLT) bcopy(dst->sa_data, &af, sizeof(af));
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201610201348.u9KDmTpE022296>