4 files changed, 39 insertions, 22 deletions

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index b8f648927a2..96ebf32a58a 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -4802,15 +4802,19 @@ check_wal_buffers(int *newval, void **extra, GucSource source)
 /*
  * Read the control file, set respective GUCs.
  *
- * This is to be called during startup, unless in bootstrap mode, where no
- * control file yet exists.  As there's no shared memory yet (its sizing can
- * depend on the contents of the control file!), first store data in local
- * memory. XLOGShemInit() will then copy it to shared memory later.
+ * This is to be called during startup, including a crash recovery cycle,
+ * unless in bootstrap mode, where no control file yet exists.  As there's no
+ * usable shared memory yet (its sizing can depend on the contents of the
+ * control file!), first store the contents in local memory. XLOGShemInit()
+ * will then copy it to shared memory later.
+ *
+ * reset just controls whether previous contents are to be expected (in the
+ * reset case, there's a dangling pointer into old shared memory), or not.
  */
 void
-LocalProcessControlFile(void)
+LocalProcessControlFile(bool reset)
 {
-	Assert(ControlFile == NULL);
+	Assert(reset || ControlFile == NULL);
 	ControlFile = palloc(sizeof(ControlFileData));
 	ReadControlFile();
 }
@@ -4884,20 +4888,13 @@ XLOGShmemInit(void)
 	}
 #endif
 
-	/*
-	 * Already have read control file locally, unless in bootstrap mode. Move
-	 * local version into shared memory.
-	 */
+
+	XLogCtl = (XLogCtlData *)
+		ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog);
+
 	localControlFile = ControlFile;
 	ControlFile = (ControlFileData *)
 		ShmemInitStruct("Control File", sizeof(ControlFileData), &foundCFile);
-	if (localControlFile)
-	{
-		memcpy(ControlFile, localControlFile, sizeof(ControlFileData));
-		pfree(localControlFile);
-	}
-	XLogCtl = (XLogCtlData *)
-		ShmemInitStruct("XLOG Ctl", XLOGShmemSize(), &foundXLog);
 
 	if (foundCFile || foundXLog)
 	{
@@ -4908,11 +4905,24 @@ XLOGShmemInit(void)
 		WALInsertLocks = XLogCtl->Insert.WALInsertLocks;
 		LWLockRegisterTranche(LWTRANCHE_WAL_INSERT,
 							  "wal_insert");
+
+		if (localControlFile)
+			pfree(localControlFile);
 		return;
 	}
 	memset(XLogCtl, 0, sizeof(XLogCtlData));
 
 	/*
+	 * Already have read control file locally, unless in bootstrap mode. Move
+	 * contents into shared memory.
+	 */
+	if (localControlFile)
+	{
+		memcpy(ControlFile, localControlFile, sizeof(ControlFileData));
+		pfree(localControlFile);
+	}
+
+	/*
 	 * Since XLogCtlData contains XLogRecPtr fields, its sizeof should be a
 	 * multiple of the alignment for same, so no extra alignment padding is
 	 * needed here.
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index e4f8f597c60..160b555294f 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -951,7 +951,7 @@ PostmasterMain(int argc, char *argv[])
 	CreateDataDirLockFile(true);
 
 	/* read control file (error checking and contains config) */
-	LocalProcessControlFile();
+	LocalProcessControlFile(false);
 
 	/*
 	 * Initialize SSL library, if specified.
@@ -3829,6 +3829,10 @@ PostmasterStateMachine(void)
 		ResetBackgroundWorkerCrashTimes();
 
 		shmem_exit(1);
+
+		/* re-read control file into local memory */
+		LocalProcessControlFile(true);
+
 		reset_shared(PostPortNumber);
 
 		StartupPID = StartupDataBase();
@@ -4808,8 +4812,11 @@ SubPostmasterMain(int argc, char *argv[])
 	/* Read in remaining GUC variables */
 	read_nondefault_variables();
 
-	/* (re-)read control file (contains config) */
-	LocalProcessControlFile();
+	/*
+	 * (re-)read control file, as it contains config. The postmaster will
+	 * already have read this, but this process doesn't know about that.
+	 */
+	LocalProcessControlFile(false);
 
 	/*
 	 * Reload any libraries that were preloaded by the postmaster.  Since we
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 46b662266b5..dfd52b3c87e 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3718,7 +3718,7 @@ PostgresMain(int argc, char *argv[],
 		CreateDataDirLockFile(false);
 
 		/* read control file (error checking and contains config ) */
-		LocalProcessControlFile();
+		LocalProcessControlFile(false);
 
 		/* Initialize MaxBackends (if under postmaster, was done already) */
 		InitializeMaxBackends();
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index e0635ab4e68..7213af0e813 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -261,7 +261,7 @@ extern XLogRecPtr GetFakeLSNForUnloggedRel(void);
 extern Size XLOGShmemSize(void);
 extern void XLOGShmemInit(void);
 extern void BootStrapXLOG(void);
-extern void LocalProcessControlFile(void);
+extern void LocalProcessControlFile(bool reset);
 extern void StartupXLOG(void);
 extern void ShutdownXLOG(int code, Datum arg);
 extern void InitXLOGAccess(void);