linux-kernel - Re: [PATCH v1 1/4] lib: introduce copy_struct_from

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Message-ID: <CAHk-=wgcHw-O1sXw2jfJEHSVa2xmJcP9dzUmy71Cqk7_wVLSFQ@mail.gmail.com>
Date:   Wed, 25 Sep 2019 11:13:18 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Aleksa Sarai <cyphar@...har.com>, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Christian Brauner <christian@...uner.io>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        GNU C Library <libc-alpha@...rceware.org>,
        Linux API <linux-api@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/4] lib: introduce copy_struct_from_user() helper

On Wed, Sep 25, 2019 at 11:04 AM Al Viro <viro@...iv.linux.org.uk> wrote:
>
> IMO it's better to lift reading the first word out of the loop, like this:
>   ...
> Do you see any problems with that variant?

That looks fine to me too.

It's a bit harder for humans to read because of how it reads the word
from user space one iteration early, but from a code generation
standpoint it probably is better.

So slightly subtler source code, and imho harder to read, but it looks
correct to me.

             Linus