Feedback-ID: i0fe9450f:Fastmail
Date: Mon, 6 Apr 2026 14:41:04 +0900
From: Michael Paquier <michael@paquier.xyz>
To: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Cc: pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Convert all remaining subsystems to use the new shmem
 allocation
Message-ID: <adNHcBVJO5gIOp1l@paquier.xyz>
References: <E1w9WsZ-0039AO-1J@gemulon.postgresql.org>
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On Sun, Apr 05, 2026 at 11:27:44PM +0000, Heikki Linnakangas wrote:
> Convert all remaining subsystems to use the new shmem allocation API
>=20
> This removes all remaining uses of ShmemInitStruct() and
> ShmemInitHash() from built-in code.
>
> src/backend/utils/misc/injection_point.c           |  57 ++++---

drongo, that compiles without USE_INJECTION_POINTS, is complaining
about this bit around line 240:
const ShmemCallbacks InjectionPointShmemCallbacks =3D {
#ifdef USE_INJECTION_POINTS
    .request_fn =3D InjectionPointShmemRequest,
    .init_fn =3D InjectionPointShmemInit,
#endif
};

Link:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Ddrongo&dt=3D2026-=
04-06%2004%3A09%3A20
And the error:
=2E./pgsql/src/backend/utils/misc/injection_point.c(240): error C2059: synt=
ax error: '}'

Why not putting the whole InjectionPointShmemCallbacks inside a
USE_INJECTION_POINTS block?  We should not care about shmem
allocations when --enable-injection-points is not used.

subsystemlist.h expects the callbacks to always be defined, so your
intention is to have no ifdefs there.  Still, it seems a bit pointless
to me to define callbacks we are not going to use depending on the
build options evoked?  Attached is one idea, which I doubt you'll
like.  :)
--
Michael

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diff --git a/src/include/storage/subsystemlist.h b/src/include/storage/subs=
ystemlist.h
index 5e092552c725..9ad619080be2 100644
--- a/src/include/storage/subsystemlist.h
+++ b/src/include/storage/subsystemlist.h
@@ -79,7 +79,9 @@ PG_SHMEM_SUBSYSTEM(SyncScanShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(AsyncShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(StatsShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(WaitEventCustomShmemCallbacks)
+#ifdef USE_INJECTION_POINTS
 PG_SHMEM_SUBSYSTEM(InjectionPointShmemCallbacks)
+#endif
 PG_SHMEM_SUBSYSTEM(WaitLSNShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(LogicalDecodingCtlShmemCallbacks)
 PG_SHMEM_SUBSYSTEM(DataChecksumsShmemCallbacks)
diff --git a/src/backend/utils/misc/injection_point.c b/src/backend/utils/m=
isc/injection_point.c
index a7c99e097ea4..aa455c62bcc0 100644
--- a/src/backend/utils/misc/injection_point.c
+++ b/src/backend/utils/misc/injection_point.c
@@ -230,19 +230,15 @@ injection_point_cache_get(const char *name)
=20
 	return NULL;
 }
-#endif							/* USE_INJECTION_POINTS */
=20
 const ShmemCallbacks InjectionPointShmemCallbacks =3D {
-#ifdef USE_INJECTION_POINTS
 	.request_fn =3D InjectionPointShmemRequest,
 	.init_fn =3D InjectionPointShmemInit,
-#endif
 };
=20
 /*
  * Reserve space for the dynamic shared hash table
  */
-#ifdef USE_INJECTION_POINTS
 static void
 InjectionPointShmemRequest(void *arg)
 {
@@ -259,7 +255,7 @@ InjectionPointShmemInit(void *arg)
 	for (int i =3D 0; i < MAX_INJECTION_POINTS; i++)
 		pg_atomic_init_u64(&ActiveInjectionPoints->entries[i].generation, 0);
 }
-#endif
+#endif							/* USE_INJECTION_POINTS */
=20
 /*
  * Attach a new injection point.

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