linux-kernel - Re: [POC] mce: replace TIF_MCE_NOTIFY with TIF_USER_RETURN

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Date:	Sun, 05 Jun 2011 16:55:42 +0300
From:	Avi Kivity <avi@...hat.com>
To:	"Luck, Tony" <tony.luck@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [POC] mce: replace TIF_MCE_NOTIFY with TIF_USER_RETURN_NOTIFY

On 05/28/2011 03:35 AM, Luck, Tony wrote:
> [Oops - forgot to Cc: LKML!]
> Ingo wrote:
> >  We already have a generic facility to do such things at
> >  return-to-userspace: _TIF_USER_RETURN_NOTIFY.
>
> This is what it might look like if we replaced the current use
> of TIF_MCE_NOTIFY with TIF_USER_RETURN_NOTIFY in mce.c
>
> Question: the notifier can potentially send signals to the current
> process - so should the check for _TIF_USER_RETURN_NOTIFY in do_notify_resume
> be moved before the check for _TIF_SIGPENDING?

It is unnecessary.  If a signal is raised, then _TIF_SIGPENDING will be 
ORed into the flags, and when we try to return again, we'll notice it 
and go right back into do_notify_resume().

> Would doing do be a problem
> for the existing user of user-return-notifiers (kvm)?

It would not be a problem.  The orders of the checks should be immaterial.

<snip patch>

Looks good.

-- 
error compiling committee.c: too many arguments to function

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