# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1679670884 -3600
# Node ID 754959243588dbc143ca0140ee2e0fd7bf149395
# Parent  f2f170ce32e85b36c7feccb5f24f51f59c9f90f8
Sought to prevent a race condition when deleting pipe paging coordinators.

diff -r f2f170ce32e8 -r 754959243588 libfsserver/include/fsserver/pipe_paging.h
--- a/libfsserver/include/fsserver/pipe_paging.h	Fri Mar 24 00:46:26 2023 +0100
+++ b/libfsserver/include/fsserver/pipe_paging.h	Fri Mar 24 16:14:44 2023 +0100
@@ -1,7 +1,7 @@
 /*
  * A pipe paging coordinator, permitting memory sharing pipe endpoints.
  *
- * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk>
+ * Copyright (C) 2021, 2023 Paul Boddie <paul@boddie.org.uk>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -21,6 +21,7 @@
 
 #pragma once
 
+#include <mutex>
 #include <set>
 
 #include <fsserver/notification.h>
@@ -39,6 +40,7 @@
     Memory *_memory;
     Pages *_pages;
     PageQueue *_queue;
+    std::mutex _lock;
 
     /* Regions acting as files with their own accessors. */
 
diff -r f2f170ce32e8 -r 754959243588 libfsserver/lib/pipes/pipe_pager.cc
--- a/libfsserver/lib/pipes/pipe_pager.cc	Fri Mar 24 00:46:26 2023 +0100
+++ b/libfsserver/lib/pipes/pipe_pager.cc	Fri Mar 24 16:14:44 2023 +0100
@@ -58,8 +58,6 @@
     if (_paging == NULL)
         return;
 
-    unsigned int attached = _paging->detach();
-
     /* Notify the other endpoint and unsubscribe. */
 
     _paging->notify_others(_writing ? PipePaging::WRITER : PipePaging::READER,
@@ -68,7 +66,7 @@
 
     /* Deallocate the paging coordinator if no other endpoints are active. */
 
-    if (!attached)
+    if (!_paging->detach())
     {
         delete _paging;
         _paging = NULL;
diff -r f2f170ce32e8 -r 754959243588 libfsserver/lib/pipes/pipe_paging.cc
--- a/libfsserver/lib/pipes/pipe_paging.cc	Fri Mar 24 00:46:26 2023 +0100
+++ b/libfsserver/lib/pipes/pipe_paging.cc	Fri Mar 24 16:14:44 2023 +0100
@@ -81,6 +81,8 @@
 
 unsigned int PipePaging::detach()
 {
+    std::lock_guard<std::mutex> guard(_lock);
+
     if (_active_endpoints)
         _active_endpoints--;