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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Rik van Riel <riel@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	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, lcapitulino@redhat.com,
	pbonzini@redhat.com
Subject: Re: [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit
Date: Fri, 6 Feb 2015 22:34:21 -0800	[thread overview]
Message-ID: <20150207063421.GY5418@linux.vnet.ibm.com> (raw)
In-Reply-To: <54D58C3E.50804@redhat.com>

On Fri, Feb 06, 2015 at 10:53:34PM -0500, Rik van Riel wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> 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?

I would prefer a new series, in order to prevent possible future
confusion.

							Thanx, Paul

> Frederic, I will also add the cleanup you suggested for patch 4/5.
> 
> - -- 
> All rights reversed
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> 


  reply	other threads:[~2015-02-07  6:34 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-05 20:23 [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest riel
2015-02-05 20:23 ` [PATCH 1/5] rcu,nohz: add state parameter to context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-06 10:15     ` Paolo Bonzini
2015-02-06 13:41       ` Paul E. McKenney
2015-02-06 17:22   ` Frederic Weisbecker
2015-02-06 18:20     ` Rik van Riel
2015-02-06 18:23       ` Frederic Weisbecker
2015-02-06 18:51         ` Rik van Riel
2015-02-06 23:15           ` Frederic Weisbecker
2015-02-07  3:53             ` Rik van Riel
2015-02-07  6:34               ` Paul E. McKenney [this message]
2015-02-07  7:14                 ` Paul E. McKenney
2015-02-07  8:30                   ` Frederic Weisbecker
2015-02-07 11:29                     ` Rik van Riel
2015-02-07 20:06                     ` Paul E. McKenney
2015-02-09 15:42                       ` Rik van Riel
2015-02-05 20:23 ` [PATCH 2/5] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER riel
2015-02-05 20:23 ` [PATCH 3/5] nohz,kvm: export context_tracking_user_enter/exit riel
2015-02-05 23:55   ` Paul E. McKenney
2015-02-05 20:23 ` [PATCH 4/5] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 18:01   ` Frederic Weisbecker
2015-02-06 23:24   ` Frederic Weisbecker
2015-02-05 20:23 ` [PATCH 5/5] nohz: add stub context_tracking_is_enabled riel
2015-02-05 23:56   ` Paul E. McKenney
2015-02-06 13:46 ` [PATCH v2 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest Frederic Weisbecker
2015-02-06 13:50   ` Paolo Bonzini
2015-02-06 16:19     ` Paul E. McKenney
2015-02-06 18:09     ` Frederic Weisbecker
2015-02-06 14:56   ` Rik van Riel
2015-02-06 18:05     ` Frederic Weisbecker
2015-02-06 15:00 ` Christian Borntraeger
2015-02-06 18:20   ` Frederic Weisbecker

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