misc/86456: arp program hangs

[Kwint]

>Number:         86456
>Category:       misc
>Synopsis:       arp program hangs
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Sep 22 12:40:06 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Kwint
>Release:        FreeBSD 4.9-RELEASE
>Organization:
VIANET
>Environment:
FreeBSD gw.vianet.lt 4.9-RELEASE FreeBSD 4.9-RELEASE #7: Mon Aug 16 16:20:58 EEST 2004     kwint at gw.vianet:/usr/src/sys/compile/GATEWAY  i386
>Description:
arp -da hangs unpredictably.
I mean some two or three times it deletes arp entries, but then doing again arp -da it hangs in the middle of deleting arp enries. I found that it just loops in rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl) function in this loop:

do {
                l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
it gets rtm->rtm_seq=0 and rtm->rtm_pid=0 every time.
>How-To-Repeat:
do continuos arp -da, I did it in shell script
or, change /usr/sbin/arp source code to continuosly do arp -da
>Fix:
      
>Release-Note:
>Audit-Trail:
>Unformatted: