When system ticks are positive, for entries in the cache
bucket, syncache_timer() ran on every tick (doing nothing
useful) instead of the supposed 3, 6, 12, and 24 seconds
later (when it's time to retransmit SYN,ACK).
When ticks are negative, syncache_timer() was scheduled
for the too far future (up to ~25 days on systems with
HZ=1000), no SYN,ACK retransmits were attempted at all,
and syncache entries added in that period that correspond
to non-established connections stay there forever.
Only HEAD and RELENG_7 are affected.
Reviewed by: silby, kmacy (earlier version)
Submitted by: Maxim Dounin, ru
82b21d0858