Re: [PATCH v1 1/5] Add a mutex to guarantee single writer to qemu_logfile handle.

["Alex Bennée" <alex.bennee@linaro.org>]

Robert Foley <robert.foley@linaro.org> writes:

> Also added qemu_logfile_init() for initializing the logfile mutex.
>
> Signed-off-by: Robert Foley <robert.foley@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

> ---
> v1
>     - changed qemu_logfile_init() to use __constructor__.
> ---
>  util/log.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/util/log.c b/util/log.c
> index 1ca13059ee..c25643dc99 100644
> --- a/util/log.c
> +++ b/util/log.c
> @@ -24,8 +24,10 @@
>  #include "qapi/error.h"
>  #include "qemu/cutils.h"
>  #include "trace/control.h"
> +#include "qemu/thread.h"
>
>  static char *logfilename;
> +static QemuMutex qemu_logfile_mutex;
>  FILE *qemu_logfile;
>  int qemu_loglevel;
>  static int log_append = 0;
> @@ -49,6 +51,11 @@ int qemu_log(const char *fmt, ...)
>      return ret;
>  }
>
> +static void __attribute__((__constructor__)) qemu_logfile_init(void)
> +{
> +    qemu_mutex_init(&qemu_logfile_mutex);
> +}
> +
>  static bool log_uses_own_buffers;
>
>  /* enable or disable low levels log */
> @@ -58,6 +65,9 @@ void qemu_set_log(int log_flags)
>  #ifdef CONFIG_TRACE_LOG
>      qemu_loglevel |= LOG_TRACE;
>  #endif
> +
> +    g_assert(qemu_logfile_mutex.initialized);
> +    qemu_mutex_lock(&qemu_logfile_mutex);
>      if (!qemu_logfile &&
>          (is_daemonized() ? logfilename != NULL : qemu_loglevel)) {
>          if (logfilename) {
> @@ -93,6 +103,7 @@ void qemu_set_log(int log_flags)
>              log_append = 1;
>          }
>      }
> +    qemu_mutex_unlock(&qemu_logfile_mutex);
>      if (qemu_logfile &&
>          (is_daemonized() ? logfilename == NULL : !qemu_loglevel)) {
>          qemu_log_close();
> @@ -230,12 +241,15 @@ void qemu_log_flush(void)
>  /* Close the log file */
>  void qemu_log_close(void)
>  {
> +    g_assert(qemu_logfile_mutex.initialized);
> +    qemu_mutex_lock(&qemu_logfile_mutex);
>      if (qemu_logfile) {
>          if (qemu_logfile != stderr) {
>              fclose(qemu_logfile);
>          }
>          qemu_logfile = NULL;
>      }
> +    qemu_mutex_unlock(&qemu_logfile_mutex);
>  }
>
>  const QEMULogItem qemu_log_items[] = {


--
Alex Bennée