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 10c392c3f03d4dfddf37c41bc3dcfa851990b1ce..4419c4b465e9339c0c76f17a83646e7a764db34c 100644 (file)
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -362,7 +362,8 @@ 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
@@ -402,9 +403,12 @@ 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;
 }