All,
We
found the problem of read() on fd getting blocked when select() returns with a
read-fd set. We were calling snmp_read() twice in our code flow and hence read()
was getting blocked. This problem is now solved without any change in the
net-snmp code.
Regards,
Suresh.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Pamidipati Suresh-G20238
Sent: Tuesday, October 03, 2006 11:49 PM
To: net-snmp-users@lists.sourceforge.net
Subject: Can we make pipefds[0] in netsnmp_callback_transport() asnon-blocking fds.?Hi All,We are using Net-snmp-5.2.2 as Agentx subagent and master agent.In Subagent, we are observing that "select()" returns with a read-fd set, but a subsequent "read()" call on that fd is getting blocked. The fd-pair being used here, is created using the "pipe()" call.We observed that read() call is blocked at line no 194 in netsnmp_callback_recv() function of snmpCallbackDomain.c file. Following is the code snippet.188 DEBUGMSGTL(("transport_callback", "hook_recv enter\n"));
189
190 while (rc < 0) {
191 #ifdef WIN32
192 rc = recv(mystuff->pipefds[0], newbuf, 1, 0);
193 #else
194 rc = read(mystuff->pipefds[0], newbuf, 1);
195 #endif
196 if (rc < 0 && errno != EINTR) {
197 break;
198 }
199 }
200We have seen this problem in Montavista linux CGE - 4.0.After going through the Net-snmp code, we found that pipefds created using pipe() call are not set as non-blocking fds.Please let us know if we change the pipefds[0] as non-blocking fds as follows, will there be any impact in the functionality of Subagent and Master agent.netsnmp_transport *
netsnmp_callback_transport(int to)
{int enable_nbio;. . .. . .rc = pipe(mydata->pipefds);
ioctl(mydata->pipefds[0], FIONBIO, &enable_nbio);
. . .. . .}Any information on this will be really helpful.Thanks,Suresh.
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