Re: [dpdk-dev] [PATCH] reset src fd field to -1 in fdset_move of vhost

[Yuanhan Liu <yliu@fridaylinux.org>]

On Thu, Dec 21, 2017 at 05:15:40PM +0800, Bing Zhao wrote:
> In the fdset_move, after copying the fd&rwfds from the src to the dst, the fd should be set to -1. Or else in some cases, there will be a fault missing. E.g:
> Before: 1 -1 3 4 -1 6 7 -1 9 10
> After: 1 10 3 4 9 6 7 -1 9 10
> Then the index7 will be returned correctly for the first time, but if another fd is to be added, it will fail.

Hi,

Have you met a real issue? I'm a bit doubt about that, since the fd array
is also guarded by "pfdset->num", which makes sure we will not access
those invalid entries (i.e. the last 2 entries in above example).

	--yliu

> Signed-off-by: Bing Zhao <bing.zhao@hxt-semitech.com>
> ---
>  lib/librte_vhost/fd_man.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c
> index 4c6fed418..48594dd7f 100644
> --- a/lib/librte_vhost/fd_man.c
> +++ b/lib/librte_vhost/fd_man.c
> @@ -63,6 +63,7 @@ fdset_move(struct fdset *pfdset, int dst, int src)
>  {
>  	pfdset->fd[dst]    = pfdset->fd[src];
>  	pfdset->rwfds[dst] = pfdset->rwfds[src];
> +	pfdset->fd[src].fd = -1;
>  }
>  
>  static void
> -- 
> 2.11.0.windows.1
>