iptables-legacy: Fix for mandatory lock waiting

Parameter 'wait' passed to xtables_lock() signals three modes of
operation, depending on its value:

 0: --wait not specified, do not wait if lock is busy
-1: --wait specified without value, wait indefinitely until lock becomes
    free
>0: Wait for 'wait' seconds for lock to become free, abort otherwise

Since fixed commit, the first two cases were treated the same apart from
calling alarm(0), but that is a nop if no alarm is pending. Fix the code
by requesting a non-blocking flock() in the second case. While at it,
restrict the alarm setup to the third case only.

Cc: Jethro Beekman <jethro@fortanix.com>
Cc: howardjohn@google.com
Cc: Antonio Ojea <antonio.ojea.garcia@gmail.com>
Closes: https://bugzilla.netfilter.org/show_bug.cgi?id=1728
Fixes: 07e2107ef0cbc ("xshared: Implement xtables lock timeout using signals")
Signed-off-by: Phil Sutter <phil@nwl.cc>

0 files changed, 0 insertions, 0 deletions