xtables: Add an interval option for xtables lock wait

ip[6]tables currently waits for 1 second for the xtables lock to be
freed if the -w option is used. We have seen that the lock is held
much less than that resulting in unnecessary delay when trying to
acquire the lock. This problem is even severe in case of latency
sensitive applications.

Introduce a new option 'W' to specify the wait interval in microseconds.
If this option is not specified, the command sleeps for 1 second by
default.

v1->v2: Change behavior to take millisecond sleep as an argument to
-w as suggested by Pablo. Also maintain current behavior for -w to
sleep for 1 second as mentioned by Liping.

v2->v3: Move the millisecond behavior to a new option as suggested
by Pablo.

v3->v4: Use select instead of usleep. Sleep every iteration for
the time specified in the "-W" argument. Update man page.

v4->v5: Fix compilation error when enabling nftables

v5->v6: Simplify -W so it only takes the interval wait in microseconds.
Bail out if -W is specific but -w is not.

Joint work with Pablo Neira.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

0 files changed, 0 insertions, 0 deletions