message: Kill trace_err. We need some sort of log file.
diff: @@ -144,8 +144,7 @@ static inline const char *gpuvis_get_tracefs_filename( char *buf, size_t buflen,
  #define GPUVIS_STR( x ) #x
  #define GPUVIS_STR_VALUE( x ) GPUVIS_STR( x )
  -static int trace_fd = -1;
  -static const char *trace_err = NULL;
  +static int trace_fd = -2;
  static int exec_tracecmd( const char *cmd )
  {
  @@ -186,21 +185,15 @@ static int exec_tracecmd( const char *cmd )
  GPUVIS_EXTERN int gpuvis_trace_init()
  {
  - if ( ( trace_fd < 0 ) && !trace_err )
  + if ( trace_fd == -2 )
  {
  char filename[ PATH_MAX ];
  // The "trace_marker" file allows userspace to write into the ftrace buffer.
  if ( !gpuvis_get_tracefs_filename( filename, sizeof( filename ), "trace_marker" ) )
  - {
  - trace_err = strerror( EACCES );
  - }
  + trace_fd = -1;
  else
  - {
  trace_fd = open( filename, O_WRONLY );
  - if ( trace_fd < 0 )
  - trace_err = strerror( errno );
  - }
  }
  return trace_fd;
  @@ -209,12 +202,8 @@ GPUVIS_EXTERN int gpuvis_trace_init()
  GPUVIS_EXTERN void gpuvis_trace_shutdown()
  {
  if ( trace_fd >= 0 )
  - {
  close( trace_fd );
  - trace_fd = -1;
  - }
  -
  - trace_err = NULL;
  + trace_fd = -2;
  }
  static int trace_printf_impl( const char *key, unsigned int val, const char *fmt, va_list ap ) GPUVIS_ATTR_PRINTF( 3, 0 );
  