From: David Miller <davem@davemloft.net>
To: adobriyan@gmail.com
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] net: fix bogus cast in skb_pagelen() and use unsigned variables
Date: Sat, 19 Nov 2016 22:12:15 -0500 (EST) [thread overview]
Message-ID: <20161119.221215.1839854526883011435.davem@davemloft.net> (raw)
In-Reply-To: <20161119010808.GF1200@avx2>
From: Alexey Dobriyan <adobriyan@gmail.com>
Date: Sat, 19 Nov 2016 04:08:08 +0300
> 1) cast to "int" is unnecessary:
> u8 will be promoted to int before decrementing,
> small positive numbers fit into "int", so their values won't be changed
> during promotion.
>
> Once everything is int including loop counters, signedness doesn't
> matter: 32-bit operations will stay 32-bit operations.
>
> But! Someone tried to make this loop smart by making everything of
> the same type apparently in an attempt to optimise it.
> Do the optimization, just differently.
> Do the cast where it matters. :^)
>
> 2) frag size is unsigned entity and sum of fragments sizes is also
> unsigned.
>
> Make everything unsigned, leave no MOVSX instruction behind.
...
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Applied to net-next.
next prev parent reply other threads:[~2016-11-20 3:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-19 1:08 [PATCH] net: fix bogus cast in skb_pagelen() and use unsigned variables Alexey Dobriyan
2016-11-20 3:12 ` David Miller [this message]
2016-11-23 12:49 ` David Laight
2016-11-23 15:35 ` Alexey Dobriyan
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