Re: [PATCH 2/2] libxl: save helper: Recheck fd events

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-04-14 at 18:31 +0100, Ian Jackson wrote:
> The save helper message reader does operates with the fd in blocking

s/does //?

> mode.  So spurious wakeups could cause it to block, unless it takes
> precautions.
> 
> Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

Acked-by: Ian Campbell <ian.campbell@citrix.com>

I think that makes both of them, but based on 0/2 I think we are
awaiting a Tested-by from Konrad (who wasn't CC-d I've done so now).

> ---
>  tools/libxl/libxl_save_callout.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
> index 40b25e4..0f392ef 100644
> --- a/tools/libxl/libxl_save_callout.c
> +++ b/tools/libxl/libxl_save_callout.c
> @@ -265,6 +265,8 @@ static void helper_stdout_readable(libxl__egc *egc, libxl__ev_fd *ev,
>      STATE_AO_GC(shs->ao);
>      int rc, errnoval;
>  
> +    revents = libxl__ev_fd_recheck(egc, ev);
> +
>      if (revents & (POLLERR|POLLPRI)) {
>          LOG(ERROR, "%s signaled POLLERR|POLLPRI (%#x)",
>              shs->stdout_what, revents);