Re: [Xen-devel] [PATCH v2 2/8] tools/livepatch: Set stdout and stderr unbuffered

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Dec 14, 2016 at 07:51:54AM +0000, Ross Lagerwall wrote:
> Using both stdout and stderr interleaved without newlines can result in
> strange output when using line buffered mode (e.g. a terminal) or when
> fully buffered (e.g. redirected to a file). Set stdout to unbuffered mode
> to fix this (stderr is always unbuffered by default).
> 
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

> ---
>  tools/misc/xen-livepatch.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/misc/xen-livepatch.c b/tools/misc/xen-livepatch.c
> index f6c7c8a..56ae5aa 100644
> --- a/tools/misc/xen-livepatch.c
> +++ b/tools/misc/xen-livepatch.c
> @@ -330,7 +330,6 @@ int action_func(int argc, char *argv[], unsigned int idx)
>          }
>  
>          printf(".");
> -        fflush(stdout);
>          usleep(DELAY);
>      } while ( ++retry < RETRIES );
>  
> @@ -416,6 +415,12 @@ int main(int argc, char *argv[])
>  {
>      int i, j = 0, ret;
>  
> +    /*
> +     * Set stdout to be unbuffered to avoid having to fflush when
> +     * printing without a newline.
> +     */
> +    setvbuf(stdout, NULL, _IONBF, 0);
> +
>      if ( argc  <= 1 )
>      {
>          show_help();
> -- 
> 2.7.4
> 

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