On Mar 18, Faidon Liambotis <parav...@debian.org> wrote: > Well, the root cause IMO is that 75-persistent-net-generator.rules is > inherently susceptible to races. It's my understanding that it's valid > for events to be triggered multiple times -- there are multiple places > in d-i that "udevadm trigger" is called, including start-udev (as > shipped by udev-udeb) which would trigger another set of "add" events > beyond the original "hotplug" one. I do not think that this is "valid" in the sense that the kernel could generate multiple add events, but removing all misuses of udevadm trigger requires some work and may not even be possible at this time.
I see that we have independently devised the same fix, I am attaching a test case and a more refined version of your patch. -- ciao, Marco
#!/bin/sh -e
rm -f /etc/udev/rules.d/70-persistent-net.rules
rmmod e1000e || true
modprobe e1000e
sleep 1
rm -f /etc/udev/rules.d/70-persistent-net.rules
iteration=0
while : ; do
iteration=$((iteration + 1))
if ! echo add > /sys/class/net/eth0/uevent; then
echo "Failed at iteration $iteration!"
exit
fi
# do not send too many events to udev because they will all be queued
# and eventually processed
if [ $iteration -eq 2500 ]; then
echo "Aborting at iteration $iteration!"
exit
fi
done
--- /lib/udev/write_net_rules.orig 2015-03-30 05:18:43.228147201 +0200
+++ /lib/udev/write_net_rules 2015-03-30 06:00:39.181085432 +0200
@@ -117,6 +117,18 @@
basename=${INTERFACE%%[0-9]*}
match="$match, KERNEL==\"$basename*\""
+# build a regular expression that matches the new rule that we want to write
+new_rule_pattern=$(echo "^SUBSYSTEM==\"net\", ACTION==\"add\"$match" | sed -re 's/([\?\*])/\\\1/g')
+
+# Double check if the new rule has already been written. This happens if
+# multiple add events are generated before the script returns and udevd
+# renames the interfaces. See #765577 for details.
+if egrep -q "$new_rule_pattern" \
+ $RO_RULES_FILE $([ -e $RULES_FILE ] && echo $RULES_FILE); then
+ unlock_rules_file
+ exit 0
+fi
+
if [ "$INTERFACE_NAME" ]; then
# external tools may request a custom name
COMMENT="$COMMENT (custom name provided by external tool)"
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