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Daniel Hilst
49e77398e4
supervise() blocks SIGCHLD across the fork but unblocks it before returning, and the caller
installs the pid afterwards:
($mon_respawn, $pid_MON) = xCAT::RespawnUtils::supervise { ... } ...;
so the assignment is outside the blocked region -- the same unprotected window that existed
before e0b0ac6, moved from xcatd into the helper that was meant to make it impossible to get
wrong. ssl_reaper matches the dead child against $pid_MON and folds the death into
$mon_respawn; a monitor dying in that gap is compared against a pid still holding 0, missed,
and the caller then overwrites both with a pid that no longer exists. !$pid_MON never fires
again, so the respawn loop never runs and xcatiport stays dead until xcatd is restarted --
the failure this PR exists to remove.
Have supervise() install them itself, which is why `state` and `pid` are now passed by
reference: the pacing state is recorded and the pid assigned while SIGCHLD is still blocked,
and only then is it unblocked, so there is no point at which a reaper can run and see either
of them stale. Nothing is left for the caller to do afterwards, so both call sites become
plain statements that read $pid_MON when they need it. The child unblocks before running its
body, as it did when the unblock sat ahead of the fork's branch. The new pid is returned as
well, for a caller that wants it inline.
Verified on a live MN (xcat54-mn, AlmaLinux 10.2, xCAT 2.19.0): the startup fork produces a
monitor holding xcatiport 3002; killing it is recovered in 5s, killing the replacement at
once in 11s -- the backoff -- and killing one that had served past the healthy interval is
recovered in 1s, with the port reclaimed and xcatd active throughout. The unit test's window
subtest, red in the preceding commit, now passes.
Signed-off-by: Daniel Hilst <392820+dhilst@users.noreply.github.com>