From d9f7ed2af581222804392f9b93dc6aaf7d8c8995 Mon Sep 17 00:00:00 2001
From: Bihong Yu <yubihong@huawei.com>
Date: Tue, 16 Jun 2020 22:08:55 +0800
Subject: [PATCH] utils: add mutex to avoid races in virfile

There are races condiction to make '/run/libvirt/qemu/dbus' directory in
virDirCreateNoFork() while concurrent start VMs, and get "failed to create
directory '/run/libvirt/qemu/dbus': File exists" error message. Add an
mutex to avoid races.

Signed-off-by:Bihong Yu <yubihong@huawei.com>
Reviewed-by:Chuan Zheng <zhengchuan@huawei.com>
Reviewed-by:alexchen <alex.chen@huawei.com>
---
 src/util/virfile.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/util/virfile.c b/src/util/virfile.c
index 20260a2..ae02a6e 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -88,6 +88,7 @@
 #include "virstring.h"
 #include "virutil.h"
 #include "virsocket.h"
+#include "virthread.h"
 
 #define VIR_FROM_THIS VIR_FROM_NONE
 
@@ -108,6 +109,9 @@ VIR_LOG_INIT("util.file");
 # define O_DIRECT 0
 #endif
 
+/* Global mutex to avoid races */
+virMutex fileLock = VIR_MUTEX_INITIALIZER;
+
 int virFileClose(int *fdptr, virFileCloseFlags flags)
 {
     int saved_errno = 0;
@@ -2612,15 +2616,18 @@ virDirCreateNoFork(const char *path,
     struct stat st;
     bool created = false;
 
+    virMutexLock(&fileLock);
     if (!((flags & VIR_DIR_CREATE_ALLOW_EXIST) && virFileExists(path))) {
         if (mkdir(path, mode) < 0) {
             ret = -errno;
             virReportSystemError(errno, _("failed to create directory '%s'"),
                                  path);
+            virMutexUnlock(&fileLock);
             goto error;
         }
         created = true;
     }
+    virMutexUnlock(&fileLock);
 
     if (stat(path, &st) == -1) {
         ret = -errno;
-- 
1.8.3.1