From: Rik van Riel <riel@redhat.com>
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
Date: Fri, 06 Feb 2015 22:53:34 -0500 [thread overview]
Message-ID: <54D58C3E.50804@redhat.com> (raw)
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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next prev parent reply other threads:[~2015-02-07 3:53 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 [this message]
2015-02-07 6:34 ` Paul E. McKenney
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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