linux-kernel - Re: [PATCH] perf, ibs: Check syscall attribute flags

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Date:	Mon, 10 Sep 2012 12:37:47 -0300
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Robert Richter <robert.richter@....com>
Cc:	David Ahern <dsahern@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf, ibs: Check syscall attribute flags

Em Mon, Sep 10, 2012 at 03:07:00PM +0200, Robert Richter escreveu:
> On 07.09.12 11:20:19, David Ahern wrote:
> > I see now... intel returns ENOTSUP if exclude_guest is not set, amd 
> > returns EINVAL if it is set.

> > For the AMD case the fallback_missing_features code kicks in for 
> > perf-top and perf-record; I just need to fix up the pr_debug for that case.

> It is EOPNOTSUP. I preferred returning EOPNOTSUP too. But then I saw
> that fallback code is implemented to work mostly with EINVAL. It seems
> to be the default answer to a syscall. ;)

> There are several pieces of code in perf that implement fallback code,
> it's hard to find it all and this already caused some bugs in the
> past. I was looking at this to unify it, but it was too much effort.

Indeed these all need to be moved to perf_ev{sel,list}__open, its
something I meant to do long ago, will try again to consolidate that.

- Arnaldo
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