On Wed, 7 Jan 2015 00:40:57 +0000 David wrote: DH> I ran into an insidious agent (snmpd) hang on Linux that had me stumped DH> for quite a while. The hang occurred when attempting to walk mib-2 and DH> always occurred during attempts to walk TCP-MIB::tcpConnTable. At first I DH> thought this might be related to my build of v5.7.3 'snmpd' (see below), DH> but I eventually discovered that this was related to the fact that the DH> system the agent was running on did not have netlink socket diagnostics DH> configured in the kernel. When this is the case the netlink DH> (TCPDIAG_GETSOCK) response returns an error; the v5.7.3 version of DH> agent/mibgroup/mibII/tcpTable.c does not handle this case and the specific DH> code ends up in an infinite wait. DH> DH> I've enclosed a patch that illustrates one way of fixing this. This simply DH> logs an error and then returns from the loop when this case is DH> encountered. The additional check for a non-zero error code isn't exactly DH> needed in this case since the original netlink message isn't requesting an DH> ACK (netlink ACKs are returned as NLMSG_ERROR message types, but with a DH> zero error code). However, I've left in this check for completeness. I've DH> also removed a redundant assignment to the 'r' pointer.
David, Thank you for investigating this issue and sending us a patch. I've applied to to all active branches which have this code. DH> * I mentioned that I thought this was originally an issue related to the DH> build. I still think there are issues with the new 'libnl3' support that DH> was added in v5.7.3. I'm not an 'autoconf' expert so I won't go into DH> details about it, but I can describe at a high level what I think is DH> wrong. Can you please file a bug with this info for the autoconf issue? Thanks, Robert ------------------------------------------------------------------------------ Dive into the World of Parallel Programming. The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Net-snmp-coders mailing list Net-snmp-coders@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
