On Tue, Jun 16, 2020 at 10:39:46PM +0800, Bihong Yu wrote: > >From d9f7ed2af581222804392f9b93dc6aaf7d8c8995 Mon Sep 17 00:00:00 2001 > From: Bihong Yu <yubihong(a)huawei.com&gt; > 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(a)huawei.com&gt; > Reviewed-by:Chuan Zheng <zhengchuan(a)huawei.com&gt; > Reviewed-by:alexchen <alex.chen(a)huawei.com&gt; > --- > 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) { Instead of adding a mutex we should get rid of the virFileExists check entirely. Instead check "errno == EEXIST && (flags & VIR_DIR_CREATE_ALLOW_EXIST)" before reporting an error. > 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; Regards, Daniel