Description of problem:
multicast sendto stuck from time to time.


Version-Release number of selected component (if applicable):
2.4.21-4 kernel
Intel e1000 5.0.43 drivers


How reproducible:


Steps to Reproduce:
1. run a program that uses multicast significantly (e.g. Spread 
http://www.spread.org ). Load it for a long time. 
2. from time to time the program will appear non-responsive. Might be 
related to transient problems in the network / link / route through 
which multicast is routed. 

strace will show it stuck forever on a sendto system call, with the 
destination address being a multicast address. 
  
Actual results:
Stuck


Expected results:
Continue to run. UDP sendto should be non-blocking no matter the 
state of the link / route

Additional info:

(gdb) bt
#0  0xb7525312 in __libc_sendto () at __libc_sendto:-1
#1  0xb75dbfbe in sendto (fd=5, buf=0x804e948, n=75, flags=0, addr=
      {__sockaddr__ = 0x804e87c, __sockaddr_at__ = 0x804e87c, 
__sockaddr_ax25__ = 0x804e87c, __sockaddr_dl__ = 0x804e87c, 
__sockaddr_eon__ = 0x804e87c, __sockaddr_in__ = 0x804e87c, 
__sockaddr_in6__ = 0x804e87c, __sockaddr_inarp__ = 0x804e87c, 
__sockaddr_ipx__ = 0x804e87c, __sockaddr_iso__ = 0x804e87c, 
__sockaddr_ns__ = 0x804e87c, __sockaddr_un__ = 0x804e87c, 
__sockaddr_x25__ = 0x804e87c}, addr_len=16) at wrapsyscall.c:222