Panic in IPv4 multicast code

Alec Kloss alec-keyword-freebsd.befd64 at
Sun Sep 7 01:17:46 UTC 2008

I've been playing around with some multicast stuff with rtpdump 
and I have what appears to be a 100%-repeatable panic on
7.1-PRERELEASE (csupped on 20080905):

(kgdb) bt
#0  doadump () at pcpu.h:196
#1  0xc078f8c7 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:418
#2  0xc078fb89 in panic (fmt=Variable "fmt" is not available.
) at /usr/src/sys/kern/kern_shutdown.c:572
#3  0xc07c406e in propagate_priority (td=0xc50c7000)
    at /usr/src/sys/kern/subr_turnstile.c:222
#4  0xc07c4f38 in turnstile_wait (ts=0xc482edc0, owner=0xc50c7000, queue=Variable "queue" is not available.
    at /usr/src/sys/kern/subr_turnstile.c:739
#5  0xc07825be in _mtx_lock_sleep (m=0xc0c4884c, tid=3300787856, opts=0, file=0x0,
    line=0) at /usr/src/sys/kern/kern_mutex.c:420
#6  0xc087051f in ip_output (m=0xc4b7f600, opt=0x0, ro=0xe7155b20, flags=34, imo=0x0,
    inp=0x0) at /usr/src/sys/netinet/ip_output.c:305
#7  0xc07e74e5 in sosend_generic (so=0xc4caf340, addr=0xc49b18e0, uio=0xe7155be8,
    top=0xc4b7f600, control=0x0, flags=0, td=0xc4be0690)
    at /usr/src/sys/kern/uipc_socket.c:1246
#8  0xc07e2fff in sosend (so=0xc4caf340, addr=0xc49b18e0, uio=0xe7155be8, top=0x0,
    control=0x0, flags=0, td=0xc4be0690) at /usr/src/sys/kern/uipc_socket.c:1292
#9  0xc07e9d86 in kern_sendit (td=0xc4be0690, s=4, mp=0xe7155c64, flags=0, control=0x0,
    segflg=UIO_USERSPACE) at /usr/src/sys/kern/uipc_syscalls.c:805
#10 0xc07ecfd1 in sendit (td=0xc4be0690, s=4, mp=0xe7155c64, flags=0)
    at /usr/src/sys/kern/uipc_syscalls.c:742
#11 0xc07ed0e8 in sendto (td=0xc4be0690, uap=0xe7155cfc)
    at /usr/src/sys/kern/uipc_syscalls.c:857
#12 0xc0aa14a5 in syscall (frame=0xe7155d38) at /usr/src/sys/i386/i386/trap.c:1090
#13 0xc0a87920 in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:255
#14 0x00000033 in ?? ()

According to the comments at kern/subr_turnstile.c:222 I'm supposed
to be looking for another thread to blame for the issue... does
anyone have any thoughts about how to go about doing that?

Interestingly, I have another similarly-configured (but radically
different hardware) system that seems to do this okay.   That
system is currently running some older version of RELENG_7, but I'm
in process updating it to the same version as the troublesome

The troublesome system is using the em driver, the working system
is using rl, if there's something about the NIC that's involved.

Alec Kloss  alec at   IM: angryspamhater at
PGP key at
"No Bunny!" -- Simon,
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