Re: [dpdk-dev] [PATCH] net/failsafe: safer subdev iterator

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 17 Aug 2017 17:52:09 +0200
Gaetan Rivet <gaetan.rivet@6wind.com> wrote:

> The sub_device iterator macro should follow the general gist of the
> tailq API for an easier understanding and safer use.
> 
> Once the loop has finished, the iterator should be set to NULL.
> If no sub_device was iterated upon, the iterator should still be NULL.
> 
> Signed-off-by: Gaetan Rivet <gaetan.rivet@6wind.com>
> ---
>  drivers/net/failsafe/failsafe_private.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/net/failsafe/failsafe_private.h b/drivers/net/failsafe/failsafe_private.h
> index 0361cf4..6fa8de5 100644
> --- a/drivers/net/failsafe/failsafe_private.h
> +++ b/drivers/net/failsafe/failsafe_private.h
> @@ -222,6 +222,7 @@ extern int mac_from_arg;
>   */
>  #define FOREACH_SUBDEV_STATE(s, i, dev, state)				\
>  	for (i = fs_find_next((dev), 0, state);				\
> +	     ((s = NULL) == NULL) &&					\
I assume you are trying to do assignment inside an expression and  just expect that
to always to be true and go onto next part of assignment. This is a convulted
way to put code in the loop iterator.

But this macro is way too complex. Please break it up into inline functions or
figure out how to simplify the logic better.