--- /dev/null
+#! @PYTHON@
+
+import os
+import re
+import stat
+import sys
+
+if "--help" in sys.argv:
+ sys.stdout.write("""\
+ovs-check-dead-ifs: Check for packet sockets for nonexistent network devices.
+
+One side effect of the "force-reload-kmod" command that reloads the
+Open vSwitch kernel module is that all the network devices that the
+Open vSwitch kernel module implemented get destroyed and then replaced
+by new instances with the same names. Unfortunately, programs that
+are listening for packets on the original network devices will not
+receive packets that arrive on the new instances. This causes some
+services, such as DHCP, to silently fail. This program looks for such
+problems and, if it finds any, prints information about programs that
+are in such a state. The system administrator should then take some
+action to fix the problem, such as restarting these programs.
+""")
+ sys.exit(0)
+elif len(sys.argv) > 1:
+ sys.stderr.write("ovs-check-dead-ifs: no arguments or options accepted "
+ "(use --help for help)\n")
+ sys.exit(1)
+
+# Get the set of all valid ifindexes.
+#
+# 0 is always valid for our purposes because it means "any interface".
+valid_ifindexes = set([])
+for ifname in os.listdir("/sys/class/net"):
+ fn = "/sys/class/net/%s/ifindex" % ifname
+ try:
+ valid_ifindexes.add(int(open(fn).readline()))
+ except IOError:
+ pass
+ except ValueError:
+ print "%s: unexpected format\n" % fn
+
+# Get inodes for all packet sockets whose ifindexes don't exist.
+invalid_inodes = set()
+f = open("/proc/net/packet")
+f.readline() # Skip header line.
+for line in f:
+ fields = line.split()
+ ifindex = int(fields[4])
+ if ifindex not in valid_ifindexes:
+ invalid_inodes.add(int(fields[8]))
+f.close()
+
+if not invalid_inodes:
+ sys.exit(0)
+
+# Now find the processes that are using those packet sockets.
+inode_re = re.compile(r'socket:\[([0-9]+)\]$')
+bad_pids = set()
+for pid in os.listdir("/proc"):
+ try:
+ pid = int(pid)
+ except ValueError:
+ continue
+
+ for fd in os.listdir("/proc/%d/fd" % pid):
+ try:
+ fd = int(fd)
+ except ValueError:
+ continue
+
+ try:
+ s = os.stat("/proc/%d/fd/%d" % (pid, fd))
+ except OSError:
+ continue
+
+ if not stat.S_ISSOCK(s.st_mode):
+ continue
+
+ try:
+ linkname = os.readlink("/proc/%d/fd/%d" % (pid, fd))
+ except OSError:
+ continue
+
+ m = inode_re.match(linkname)
+ if not m:
+ continue
+
+ inode = int(m.group(1))
+ if inode in invalid_inodes:
+ bad_pids.add(pid)
+
+if bad_pids:
+ print """
+The following processes are listening for packets to arrive on network devices
+that no longer exist. You may want to restart them."""
+ os.execvp("ps", ["ps"] + ["%s" % pid for pid in bad_pids])
.IP 6.
Restores the kernel configuration state that was saved in step 3.
.
-.PP
-The steps above are often enough to hot-upgrade a new kernel module
-with only a few seconds of downtime. DHCP is a common problem: if the
-ISC DHCP client is running on an OVS internal interface, then it will
-have to be restarted after completing the above procedure.
+.IP 7.
+Checks for daemons that may need to be restarted because they have
+packet sockets that are listening on old instances of Open vSwitch
+kernel interfaces and, if it finds any, prints a warning on stdout.
+DHCP is a common example: if the ISC DHCP client is running on an OVS
+internal interface, then it will have to be restarted after completing
+the above procedure. (It would be nice if \fBovs\-ctl\fR could restart
+daemons automatically, but the details are far too specific to a
+particular distribution and installation.)
.
.PP
\fBforce\-kmod\-reload\fR internally stops and starts OVS, so it
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