From 03f06ff383eaeb80e1ad1f2aa496ab0cb283f3da Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 1 Feb 2014 16:21:07 -0500 Subject: [PATCH] Fix some more bugs in signal handlers and process shutdown logic. WalSndKill was doing things exactly backwards: it should first clear MyWalSnd (to stop signal handlers from touching MyWalSnd->latch), then disown the latch, and only then mark the WalSnd struct unused by clearing its pid field. Also, WalRcvSigUsr1Handler and worker_spi_sighup failed to preserve errno, which is surely a requirement for any signal handler. Per discussion of recent buildfarm failures. Back-patch as far as the relevant code exists. --- src/backend/replication/walsender.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c index bbde1c32e73..7b44f9b0443 100644 --- a/src/backend/replication/walsender.c +++ b/src/backend/replication/walsender.c @@ -920,17 +920,23 @@ InitWalSnd(void) static void WalSndKill(int code, Datum arg) { - Assert(MyWalSnd != NULL); + WalSnd *walsnd = MyWalSnd; + + Assert(walsnd != NULL); + + /* + * Clear MyWalSnd first; then disown the latch. This is so that signal + * handlers won't try to touch the latch after it's no longer ours. + */ + MyWalSnd = NULL; + + DisownLatch(&walsnd->latch); /* * Mark WalSnd struct no longer in use. Assume that no lock is required * for this. */ - MyWalSnd->pid = 0; - DisownLatch(&MyWalSnd->latch); - - /* WalSnd struct isn't mine anymore */ - MyWalSnd = NULL; + walsnd->pid = 0; } /*