Message-ID: <54D58C3E.50804@redhat.com>
Date: Fri, 06 Feb 2015 22:53:34 -0500
From: Rik van Riel <riel@redhat.com>
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To: Frederic Weisbecker <fweisbec@gmail.com>
CC: kvm@vger.kernel.org, borntraeger@de.ibm.com, linux-kernel@vger.kernel.org,
        mtosatti@redhat.com, mingo@kernel.orgm, ak@linux.intel.com,
        oleg@redhat.com, masami.hiramatsu.pt@hitachi.com,
        paulmck@linux.vnet.ibm.com, lcapitulino@redhat.com,
        pbonzini@redhat.com
Subject: Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit
References: <1423167832-17609-1-git-send-email-riel@redhat.com> <1423167832-17609-2-git-send-email-riel@redhat.com> <20150206172209.GC21905@lerouge> <54D505E5.9000003@redhat.com> <20150206182258.GH21905@lerouge> <54D50D4C.8010505@redhat.com> <20150206231511.GA18934@lerouge>
In-Reply-To: <20150206231511.GA18934@lerouge>
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On 02/06/2015 06:15 PM, Frederic Weisbecker wrote:

> Just a few things then:
> 
> 1) In this case rename context_tracking_user_enter/exit() to 
> context_tracking_enter() and context_tracking_exit(), since it's
> not anymore about user only but about any generic context.
> 
> 2) We have the "WARN_ON_ONCE(!current->mm);" condition that is a
> debug check specific to userspace transitions because kernel
> threads aren't expected to resume to userspace. Can we also expect
> that we never switch to/from guest from a kernel thread? AFAICS
> this happens from an ioctl (thus user task) in x86 for kvm. But I
> only know this case.
> 
> 3) You might want to update a few comments that assume we only deal
> with userspace transitions.
> 
> 4) trace_user_enter/exit() should stay user-transitions specific.

Paul, would you like me to send follow-up patches with the cleanups
suggested by Frederic, or would you prefer me to send a new series
with the cleanups integrated?

Frederic, I will also add the cleanup you suggested for patch 4/5.

- -- 
All rights reversed
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