tcpdump mailing list archives
Re: SEGFAULT when using multiple
From: Geoffrey Bugniot <g.bugniot () gmail com>
Date: Thu, 12 Jul 2012 12:08:58 +0000 (UTC)
Guy Harris <guy <at> alum.mit.edu> writes:
Somebody who works on the PF_PACKET socket code in the Linux kernel? My *guess* is that there's something wrong with the code that handles memory-mapped access to the socket (if it weren't using the memory-mapped code, it might not be any less likely to panic, but it might be less likely to get a segmentation fault in user-mode code) when more than one process is using it. netsniff-ng: http://netsniff-ng.org/ apparently also uses memory-mapped access to PF_PACKET sockets, and doesn't use libpcap; see what happens if you compile it for your embedded board and try to run two instances of it. If you have problems with that, then libpcap isn't involved at all, and you'd need to get some of the Linux networking code developers involved. (If that works, then it is probably still at least in part a Linux kernel issue, given that you're getting kernel panics, but there *might* also be an issue with how libpcap is using the memory-mapped mechanism.)
OK, I'v just cross-compiled netsniff-ng, and run it on my board. With only one instance of netsniff-ng, my board reboot. If I disable all my network interfaces (ifdown -a), no reboot, netsniff-ng just don't find an interface. With gdb, I notice that my board reboots after the last instruction of __init_stage_fallback_dev function (from netsniff-ng's code). This function is use to initialize the listening interface (i.e: eth0). So, I think the problem is not libpcap. The problem might be the hardware or the kernel configuration... - This is the tcpdump-workers list. Visit https://cod.sandelman.ca/ to unsubscribe.
Current thread:
- SEGFAULT when using multiple "instances" of libpcap Geoffrey Bugniot (Jul 11)
- Re: SEGFAULT when using multiple "instances" of libpcap Guy Harris (Jul 11)
- Re: SEGFAULT when using multiple Geoffrey Bugniot (Jul 12)
- Re: SEGFAULT when using multiple Michael Richardson (Jul 13)
- Re: SEGFAULT when using multiple Geoffrey Bugniot (Jul 12)
- Re: SEGFAULT when using multiple Geoffrey Bugniot (Aug 10)
- Re: SEGFAULT when using multiple "instances" of libpcap Guy Harris (Jul 11)