tun/tap: Bad packets sent to kernel via tun/tap interface - vpp

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author	Steven <sluong@cisco.com>	2017-09-26 15:58:24 -0700
committer	Damjan Marion <dmarion.lists@gmail.com>	2017-09-28 00:09:15 +0000
commit	4ff586d1c6fc5c40e1548cd6f221a8a7f3ad033b (patch)
tree	bd2d739d9c4998b1581bae1a7be408b4bfba6ef4 /doxygen/layout.xml
parent	75a17ecddc9dc579a3aecfc5b53cbb60e993965f (diff)

tun/tap: Bad packets sent to kernel via tun/tap interface

It was observed that under heavy traffic, VPP accidentally sent traffic with the wrong source and destination to the tun/tap interface. Traffic appears to be sent to the wrong direction. This problem is only seen when worker thread is configured. When worker thread is used, TX and RX may reside in different core. Yet both TX and RX threads are sharing the same global variable, namely iovecs without any mutex or memory barrier protection. This creates a race condition when heavy traffic is blasted to VPP, like 1000 pps. We could create a mutex or memory barrier to ensure atomic memory access. But why bother? It is a lot cheaper to just decouple the iovecs such that TX and RX have their own iovecs. Change-Id: I86a5a19bd8de54d54f32e1f0845bae6a81bbf686 Signed-off-by: Steven <sluong@cisco.com>

Diffstat (limited to 'doxygen/layout.xml')

0 files changed, 0 insertions, 0 deletions

/* *------------------------------------------------------------------ * Copyright (c) 1997-2016 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include <stdio.h> #include <time.h> #include <string.h> int main (int argc, char **argv) { time_t now; FILE *ofp; char *dateval; char *username; char *userstr; char *datestr; int i; char propname[32]; char *propvalue; char timestr[64]; char *cp; if (argc < 4) { printf ("usage: mkversion ostype version outputfile\n"); exit (1); } ofp = fopen (argv[3], "w"); if (ofp == NULL) { printf ("Couldn't create %s\n", argv[3]); exit (1); } now = time (0); fprintf (ofp, "/*\n"); fprintf (ofp, " * G2 Version Stamp, %s", ctime (&now)); fprintf (ofp, " * Automatically generated, hand edits are pointless.\n"); fprintf (ofp, " */\n\n"); fprintf (ofp, "const char *version_string = \"G2 (%s) major version %s\";\n", argv[1], argv[2]); username = (char *) cuserid (0); strcpy(timestr, ctime(&now)); cp = timestr; while (*cp) { cp++; } if (*--cp == '\n') *cp = 0; fprintf (ofp, "const char *minor_v_string = \"Built by %s at %s\";\n", username, timestr); exit (0); }


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