From: Álvaro Herrera <alvherre@kurilemu.de>
Date: Thu, 16 Apr 2026 20:27:04 +0000 (+0200)
Subject: Add missing initialization
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=05c401d5786a05ea630e884ffa492aa01683d15b;p=thirdparty%2Fpostgresql.git

Add missing initialization

The backend running REPACK can check DecodingWorkerShared->initialized
before the worker could have the chance to initialize it, possibly
leading to wrong behavior.

While at it, remove DecodingWorkerShared->worker_dsm_segment, because
that doesn't actually need to be in shared memory; a simple local-memory
global variable is enough.

Oversights in commit 28d534e2ae0a.

Author: Antonin Houska <ah@cybertec.at>
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Discussion: https://postgr.es/m/18181295-8375-4789-ad32-269d78d6001e@gmail.com
---

diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c
index 58e3867246f..67364cc60e3 100644
--- a/src/backend/commands/repack.c
+++ b/src/backend/commands/repack.c
@@ -3311,6 +3311,7 @@ start_repack_decoding_worker(Oid relid)
 		BUFFERALIGN(REPACK_ERROR_QUEUE_SIZE);
 	seg = dsm_create(size, 0);
 	shared = (DecodingWorkerShared *) dsm_segment_address(seg);
+	shared->initialized = false;
 	shared->lsn_upto = InvalidXLogRecPtr;
 	shared->done = false;
 	SharedFileSetInit(&shared->sfs, seg);
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 362e0766c41..b17edd771e2 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -44,6 +44,9 @@ static bool am_repack_worker = false;
 /* The WAL segment being decoded. */
 static XLogSegNo repack_current_segment = 0;
 
+/* Our DSM segment, for shutting down */
+static dsm_segment *worker_dsm_segment = NULL;
+
 /*
  * Keep track of the table we're processing, to skip logical decoding of data
  * from other relations.
@@ -78,9 +81,9 @@ RepackWorkerMain(Datum main_arg)
 		ereport(ERROR,
 				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				errmsg("could not map dynamic shared memory segment"));
+	worker_dsm_segment = seg;
 
 	shared = (DecodingWorkerShared *) dsm_segment_address(seg);
-	shared->dsm_seg = seg;
 
 	/* Arrange to signal the leader if we exit. */
 	before_shmem_exit(RepackWorkerShutdown, PointerGetDatum(shared));
@@ -176,7 +179,7 @@ RepackWorkerShutdown(int code, Datum arg)
 				   PROCSIG_REPACK_MESSAGE,
 				   shared->backend_proc_number);
 
-	dsm_detach(shared->dsm_seg);
+	dsm_detach(worker_dsm_segment);
 }
 
 bool
diff --git a/src/include/commands/repack_internal.h b/src/include/commands/repack_internal.h
index 3ff64444351..6a85cee8910 100644
--- a/src/include/commands/repack_internal.h
+++ b/src/include/commands/repack_internal.h
@@ -107,7 +107,6 @@ typedef struct DecodingWorkerShared
 	PGPROC	   *backend_proc;
 	pid_t		backend_pid;
 	ProcNumber	backend_proc_number;
-	dsm_segment *dsm_seg;
 
 	/*
 	 * Memory the queue is located in.