linux-kernel - Re: [PATCH v14] x86, mce: Add memcpy

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Message-ID: <CA+8MBbKn5DU22RHPYR=vKWpKd1aBu4dm5p57R5U5WTb7KCpMVQ@mail.gmail.com>
Date:	Fri, 11 Mar 2016 14:10:18 -0800
From:	Tony Luck <tony.luck@...il.com>
To:	Mika Penttilä <mika.penttila@...tfour.com>,
	Ingo Molnar <mingo@...nel.org>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andy Lutomirski <luto@...capital.net>,
	"Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v14] x86, mce: Add memcpy_mcsafe()

On Thu, Mar 10, 2016 at 11:37 AM, Luck, Tony <tony.luck@...el.com> wrote:
>> But you return 0 == false for success and 1 == true for failure.
>
> Aaargh!  -ETOOMUCHSHELLSCRIPTPROGRAMMING
>
> -Tony

Options to fix this:
1) Just change the comments in the code.
     This seems like it would confuse people as I thing most people
     would expect the "true" return to mean the copy succeeded.
2) Reverse the return values.
     Better that option 1 - but doesn't leave scope to return a count
     if some future user does want to know where the copy failed.
3) Change the return type back from "bool" to "int"
     0 == success, non-zero == fail (with option to put the non-copied
byte count in later).
4) Something else

-Tony