From: Andres Freund <andres@anarazel.de>
Date: Thu, 7 Apr 2022 06:35:56 +0000 (-0700)
Subject: pgstat: prevent fix pgstat_reinit_entry() from zeroing out lwlock.
X-Git-Tag: REL_15_BETA1~264
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=81ae9e65887476b4c55aaad276a8010a459a41ce;p=thirdparty%2Fpostgresql.git

pgstat: prevent fix pgstat_reinit_entry() from zeroing out lwlock.

Zeroing out an lwlock in a normal build turns out to not trigger any alarms,
if nobody can use the lwlock at that moment (as the case here). But with
--disable-spinlocks --disable-atomics, the sema field needs to be initialized.

We probably should make sure that this fails on more common configurations as
well...

Per buildfarm animal rorqual
---

diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index a32740b2f6e..b270c504ea6 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -292,8 +292,8 @@ pgstat_reinit_entry(PgStat_Kind kind, PgStatShared_HashEntry *shhashent)
 
 	/* reinitialize content */
 	Assert(shheader->magic == 0xdeadbeef);
-	memset(shheader, 0, pgstat_get_kind_info(shhashent->key.kind)->shared_size);
-	shheader->magic = 0xdeadbeef;
+	memset(pgstat_get_entry_data(kind, shheader), 0,
+		   pgstat_get_entry_len(kind));
 
 	return shheader;
 }