From: Thomas Munro <tmunro@postgresql.org>
Date: Thu, 14 Jul 2022 13:23:29 +0000 (+1200)
Subject: Don't clobber postmaster sigmask in dsm_impl_resize.
X-Git-Tag: REL_11_17~37
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=74a9ee034829153c3d5bfa270fd6372aa3147db5;p=thirdparty%2Fpostgresql.git

Don't clobber postmaster sigmask in dsm_impl_resize.

Commit 4518c798 intended to block signals in regular backends that
allocate DSM segments, but dsm_impl_resize() is also reached by
dsm_postmaster_startup().  It's not OK to clobber the postmaster's
signal mask, so only manipulate the signal mask when under the
postmaster.

Back-patch to all releases, like 4518c798.

Discussion: https://postgr.es/m/CA%2BhUKGKNpK%3D2OMeea_AZwpLg7Bm4%3DgYWk7eDjZ5F6YbozfOf8w%40mail.gmail.com
---

diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c
index 6cbfff87a1e..11d8f601037 100644
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -417,7 +417,8 @@ dsm_impl_posix_resize(int fd, off_t size)
 	 * allowed SIGUSR1 to interrupt us repeatedly (for example, due to recovery
 	 * conflicts), the retry loop might never succeed.
 	 */
-	PG_SETMASK(&BlockSig);
+	if (IsUnderPostmaster)
+		PG_SETMASK(&BlockSig);
 
 	/* Truncate (or extend) the file to the requested size. */
 	do
@@ -455,9 +456,12 @@ dsm_impl_posix_resize(int fd, off_t size)
 	}
 #endif							/* HAVE_POSIX_FALLOCATE && __linux__ */
 
-	save_errno = errno;
-	PG_SETMASK(&UnBlockSig);
-	errno = save_errno;
+	if (IsUnderPostmaster)
+	{
+		save_errno = errno;
+		PG_SETMASK(&UnBlockSig);
+		errno = save_errno;
+	}
 
 	return rc;
 }