[ovs-dev] [threads 07/23] xenserver: Make thread-safe.

[Alex Wang]

Looks good to me, thanks,


On Thu, Jul 18, 2013 at 4:15 PM, Ben Pfaff <blp at nicira.com> wrote:

> Signed-off-by: Ben Pfaff <blp at nicira.com>
> ---
>  vswitchd/xenserver.c |   23 +++++++++++------------
>  1 files changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/vswitchd/xenserver.c b/vswitchd/xenserver.c
> index 1f26e0d..bc57f0e 100644
> --- a/vswitchd/xenserver.c
> +++ b/vswitchd/xenserver.c
> @@ -17,6 +17,7 @@
>  #include "xenserver.h"
>  #include <ctype.h>
>  #include <errno.h>
> +#include <pthread.h>
>  #include <stdlib.h>
>  #include <string.h>
>  #include <unistd.h>
> @@ -26,7 +27,11 @@
>
>  VLOG_DEFINE_THIS_MODULE(xenserver);
>
> -static char *
> +/* If running on a XenServer, the XenServer host UUID as a 36-character
> string,
> + * otherwise null. */
> +static char *host_uuid;
> +
> +static void
>  read_host_uuid(void)
>  {
>      static const char filename[] = "/etc/xensource-inventory";
> @@ -40,7 +45,7 @@ read_host_uuid(void)
>          } else {
>              VLOG_INFO("%s: open: %s", filename, ovs_strerror(errno));
>          }
> -        return NULL;
> +        return;
>      }
>
>      while (fgets(line, sizeof line, file)) {
> @@ -53,27 +58,21 @@ read_host_uuid(void)
>          if (strlen(line) == leader_len + uuid_len + trailer_len
>              && !memcmp(line, leader, leader_len)
>              && !memcmp(line + leader_len + uuid_len, trailer,
> trailer_len)) {
> -            char *host_uuid = xmemdup0(line + leader_len, uuid_len);
> +            host_uuid = xmemdup0(line + leader_len, uuid_len);
>              VLOG_INFO("running on XenServer, host-uuid %s", host_uuid);
>              fclose(file);
> -            return host_uuid;
> +            return;
>          }
>      }
>      fclose(file);
>      VLOG_ERR("%s: INSTALLATION_UUID not found", filename);
> -    return NULL;
>  }
>
>  const char *
>  xenserver_get_host_uuid(void)
>  {
> -    static char *host_uuid;
> -    static bool inited;
> -
> -    if (!inited) {
> -        host_uuid = read_host_uuid();
> -        inited = true;
> -    }
> +    static pthread_once_t once = PTHREAD_ONCE_INIT;
> +    pthread_once(&once, read_host_uuid);
>      return host_uuid;
>  }
>
> --
> 1.7.2.5
>
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>
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