This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH v1 1/4] lib: introduce copy_struct_from_user() helper
- From: Linus Torvalds <torvalds at linux-foundation dot org>
- To: Al Viro <viro at zeniv dot linux dot org dot uk>
- Cc: Aleksa Sarai <cyphar at cyphar dot com>, Ingo Molnar <mingo at redhat dot com>, Peter Zijlstra <peterz at infradead dot org>, Alexander Shishkin <alexander dot shishkin at linux dot intel dot com>, Jiri Olsa <jolsa at redhat dot com>, Namhyung Kim <namhyung at kernel dot org>, Christian Brauner <christian at brauner dot io>, Rasmus Villemoes <linux at rasmusvillemoes dot dk>, GNU C Library <libc-alpha at sourceware dot org>, Linux API <linux-api at vger dot kernel dot org>, Linux Kernel Mailing List <linux-kernel at vger dot kernel dot org>
- Date: Wed, 25 Sep 2019 11:13:18 -0700
- Subject: Re: [PATCH v1 1/4] lib: introduce copy_struct_from_user() helper
- References: <20190925165915.8135-1-cyphar@cyphar.com> <20190925165915.8135-2-cyphar@cyphar.com> <CAHk-=wjFeNjhtUxQ8npmXORz5RLQU7B_3wD=45eug1+MXnuYvA@mail.gmail.com> <20190925172049.skm6ohnnxpofdkzv@yavin> <CAHk-=wjagt257WHiOr2v1Bx_3q7tuzogabw_1EnodKm0vt+-WQ@mail.gmail.com> <20190925180412.GK26530@ZenIV.linux.org.uk>
On Wed, Sep 25, 2019 at 11:04 AM Al Viro <viro@zeniv.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