ebtables: Enable locking for concurrent ebtables processes #1294
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The previous locking mechanism was not atomic, hence it was possible that a killed ebtables process would leave the lock file in place which in turn made future ebtables processes wait indefinitely for the lock to become free. Fix this by using flock(). This also simplifies code quite a bit because there is no need for a custom signal handler or an __exit routine anymore. Signed-off-by: Sven Eckelmann <sven@narfation.org>
This enables the ebtables internal locking mechanism which will avoid race conditions between multiple, concurrent ebtables calls. This is a preparation for the upcoming gluon-arp-limiter daemon, to avoid issues if upon restarting gluon-ebtables the gluon-arp-limiter daemon tries to modify the tables. Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
rotanid
added
0. type: enhancement
jplitza
approved these changes
Jan 3, 2018
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Rebased and applied. |
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These changes are to enable locking to avoid problems when multiple ebtables processes try to modify the kernel data structures at the same time. Not using a lock can result in not applied modifications (add/delete) in the kernel.
During one of my tests, such a concurrency problem resulted in a node which was suppressing all RADVs. The reason for that was an empty RADV_FILTER. This could be fixed by restarting gluon-radv-filterd (when no other ebtables process was running at the same time).
These are required for the PRs #838 and #1113.