fix_do_pg_abort_backup_v2.patch

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 0513471..c2c4ee4 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -10922,11 +10922,16 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 	{
 		XLogCtl->Insert.forcePageWrites = false;
 	}
-	WALInsertLockRelease();
 
-	/* Clean up session-level lock */
+	/*
+	 * Clean up session-level lock. To avoid interrupting before changing
+	 * the backup state by LWLockWaitForVar we change it while holding the
+	 * WAL insert lock.
+	 */
 	sessionBackupState = SESSION_BACKUP_NONE;
 
+	WALInsertLockRelease();
+
 	/*
 	 * Read and parse the START WAL LOCATION line (this code is pretty crude,
 	 * but we are not expecting any variability in the file format).
@@ -11164,6 +11169,10 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 void
 do_pg_abort_backup(void)
 {
+	/* Quick exit if we have done the backup */
+	if (XLogCtl->Insert.exclusiveBackupState == EXCLUSIVE_BACKUP_NONE)
+		return;
+
 	WALInsertLockAcquireExclusive();
 	Assert(XLogCtl->Insert.nonExclusiveBackups > 0);
 	XLogCtl->Insert.nonExclusiveBackups--;