linux-kernel - Re: [PATCH] Change judgment len position

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Message-ID: <375561cf08343abbcd4118da2272507c30311788.camel@perches.com>
Date:   Wed, 24 Oct 2018 10:18:31 -0700
From:   Joe Perches <joe@...ches.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Willy Tarreau <w@....eu>, wanghaifine@...il.com,
        David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Change judgment len position

On Wed, 2018-10-24 at 10:03 -0700, Eric Dumazet wrote:
> On Wed, Oct 24, 2018 at 9:54 AM Joe Perches <joe@...ches.com> wrote:
> 
> > I think if the point is to test for negative numbers,
> > it's clearer to do that before using min_t.and it's
> > probably clearer not to use min_t at all.
> > 
> 
> ...
> 
> >         if (len > sizeof(int))
> >                 len = sizeof(int);
> 
> It is a matter of taste really,

Agree and hence my use of 'I think' above.

> I know some people (like me) sometimes
> mixes min() and max()

Not quite sure what you mean here by mixes.
mix up?  If so, the < > inversions probably
have about the same error rate.

And I suppose there are cases where the
always set of len in uses like

	len = min(len, 4);

are more costly (len being in a slow write
speed area of memory or some such) than the
other style of

	if (len < 4)
		len = 4;

I think that min() is easier to read in most
cases.

> I would suggest that if someones wants to change the current code, a
> corresponding test would be added in tools/testing/selftests/net?