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
Created attachment 96765 [details] multicast traffic generation file
Created attachment 96766 [details] unicast packet generation script
btw with 2.4.20-18 this works OK
I have been unable to reproduce this problem. Note that UDP sendto can and will block, depeneding on system load, memory pressure, etc. If this problem is readily reproducable, please post more information, such as the output from alt-sysrq-m and alt-sysrq-t when the process is hung, and the exact steps to reproduce the problem (i.e. how many instances of what program do you run with what switches).
The main combination that causes this is: RHEL3 kernel + Intel e1000 2.X drivers from Intel + link down I think the scenario is quite clear above and I attached the program I used and the switches I used to run it.
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Same problem with stock e1000 driver from RHEL. Please refer to service request #1155558