netdev - Re: [PATCH mlx5-next v1 05/15] net/mlx5: Break encap/decap into two separated flow table creation flags

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Date:   Thu, 6 Sep 2018 19:13:56 +0300
From:   Or Gerlitz <gerlitz.or@...il.com>
To:     Leon Romanovsky <leonro@...lanox.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>, Doug Ledford <dledford@...hat.com>,
        RDMA mailing list <linux-rdma@...r.kernel.org>,
        Ariel Levkovich <lariel@...lanox.com>,
        Mark Bloch <markb@...lanox.com>,
        Or Gerlitz <ogerlitz@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        linux-netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH mlx5-next v1 05/15] net/mlx5: Break encap/decap into two
 separated flow table creation flags

On Thu, Sep 6, 2018 at 7:09 AM, Leon Romanovsky <leonro@...lanox.com> wrote:
> On Thu, Sep 06, 2018 at 12:37:17AM +0300, Or Gerlitz wrote:
>> On Wed, Sep 5, 2018 at 9:11 PM, Leon Romanovsky  wrote:
>> > On Wed, Sep 05, 2018 at 10:38:00AM -0600, Jason Gunthorpe wrote:
>> >> On Wed, Sep 05, 2018 at 08:10:25AM +0300, Leon Romanovsky wrote:
>> >> > > > -       int en_encap_decap = !!(flags & MLX5_FLOW_TABLE_TUNNEL_EN);
>> >> > > > +       int en_encap = !!(flags & MLX5_FLOW_TABLE_TUNNEL_EN_ENCAP);
>> >> > > > +       int en_decap = !!(flags & MLX5_FLOW_TABLE_TUNNEL_EN_DECAP);
>> >> > >
>> >> > > Yuk, please don't use !!.
>> >> > >
>> >> > >   bool en_decap = flags & MLX5_FLOW_TABLE_TUNNEL_EN_DECAP;
>> >> >
>> >> > We need to provide en_encap and en_decap as an input to MLX5_SET(...)
>> >> > which is passed to FW as 0 or 1.
>> >> >
>> >> > Boolean type is declared in C as int and treated as zero for false
>> >> > and any other value for true,
>> >>
>> >> No, that isn't right, the kernel uses C99's _Bool intrinsic type, which
>> >> is guaranteed to only hold 0 or 1 by the compiler.
>> >>
>> >> See types.h:
>> >>
>> >> typedef _Bool                   bool;
>> >
>> > Exciting, it took me a while to find C99 standard and relevant 6.3.1.2.
>> > Anyway, this patch didn't change previous functionality, which used "!!"
>> > convention.
>>
>> so? if we didn't do things properly prior to the patch, why not fixing it along
>> with the patch? lets fix
>
> Or,
>
> What exactly "to fix"? Both code lines:
> 1. Have correct syntax
> 2. Implement proper C99
> 3. Give same compiler code
> 4. Have same readability
>
> There is nothing to fix.
>
> And this patch is already merged, so if you truly care about this,
> please go ahead and prepare patch for whole driver, or better for
> whole kernel.

slow down, I was just supporting Jason's suggestion and said there's
no reason not to follow it.

If you don't agree with Jason, argue with him.

>  kernel git:(rdma-next) git grep "\!\!" |wc -l
> 8125