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 33a27b3a452e1c19d29faa3cdaa45a83349ba88f..44962af32cd76df5dca6b97e3910afdb5d899a1b 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;
 }