From: "Jan Beulich" <JBeulich@suse.com>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: "Russell King" <linux@arm.linux.org.uk>, <yong.zhang0@gmail.com>,
"Jeremy Fitzhardinge" <jeremy@goop.org>, <peterz@infradead.org>,
<mingo@kernel.org>, <x86@kernel.org>,
"Thomas Gleixner" <tglx@linutronix.de>,
<akpm@linux-foundation.org>, <nikunj@linux.vnet.ibm.com>,
<paulmck@linux.vnet.ibm.com>, <vatsa@linux.vnet.ibm.com>,
<virtualization@lists.linux-foundation.org>,
<xen-devel@lists.xensource.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Ingo Molnar" <mingo@redhat.com>, <rusty@rustcorp.com.au>,
<rjw@sisk.pl>, <linux-arch@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, "Keir Fraser" <keir@xen.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH 05/27] xen, cpu hotplug: Don't call cpu_bringup() in xen_play_dead()
Date: Fri, 01 Jun 2012 16:36:28 +0100 [thread overview]
Message-ID: <4FC8FD9C0200007800087DF5@nat28.tlf.novell.com> (raw)
In-Reply-To: <4FC8DC19.4000007@linux.vnet.ibm.com>
>>> On 01.06.12 at 17:13, "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
wrote:
> On 06/01/2012 06:29 PM, Jan Beulich wrote:
>
>>>>> On 01.06.12 at 11:11, "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
>> wrote:
>>> xen_play_dead calls cpu_bringup() which looks weird, because xen_play_dead()
>>> is invoked in the cpu down path, whereas cpu_bringup() (as the name
>>> suggests) is useful in the cpu bringup path.
>>
>> This might not be correct - the code as it is without this change is
>> safe even when the vCPU gets onlined back later by an external
>> entity (e.g. the Xen tool stack), and it would in that case resume
>> at the return point of the VCPUOP_down hypercall. That might
>> be a heritage from the original XenoLinux tree though, and be
>> meaningless in pv-ops context - Jeremy, Konrad?
>>
>> Possibly it was bogus/unused even in that original tree - Keir?
>>
>
>
> Thanks for your comments Jan!
>
> In case this change is wrong, the other method I had in mind was to call
> cpu_bringup_and_idle() in xen_play_dead(). (Even ARM does something similar,
> in the sense that it runs the cpu bringup code including cpu_idle(), in the
> cpu offline path, namely the cpu_die() function). Would that approach work
> for xen as well? If yes, then we wouldn't have any issues to convert xen to
> generic code.
No, that wouldn't work either afaict - the function is expected
to return.
Jan
next prev parent reply other threads:[~2012-06-01 15:36 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-01 9:10 [PATCH 00/27] Generic framework for SMP booting/CPU hotplug related code Srivatsa S. Bhat
2012-06-01 9:10 ` [PATCH 01/27] smpboot: Provide a generic method to boot secondary processors Srivatsa S. Bhat
2012-06-01 12:09 ` Srivatsa S. Bhat
2012-06-03 8:51 ` Yong Zhang
2012-06-03 11:22 ` Srivatsa S. Bhat
2012-06-04 2:18 ` Yong Zhang
2012-06-03 8:53 ` Yong Zhang
2012-06-03 11:33 ` Srivatsa S. Bhat
2012-06-03 11:39 ` Russell King - ARM Linux
2012-06-03 12:05 ` Srivatsa S. Bhat
2012-06-01 16:51 ` Sam Ravnborg
2012-06-01 22:29 ` Srivatsa S. Bhat
2012-06-04 10:32 ` Thomas Gleixner
2012-06-04 13:07 ` Srivatsa S. Bhat
2012-06-04 13:18 ` Thomas Gleixner
2012-06-04 16:53 ` Srivatsa S. Bhat
2012-06-05 5:11 ` Yong Zhang
2012-06-05 6:07 ` Srivatsa S. Bhat
2012-06-01 16:53 ` Sam Ravnborg
2012-06-01 22:41 ` Srivatsa S. Bhat
2012-06-02 15:16 ` Sam Ravnborg
2012-06-02 15:34 ` Srivatsa S. Bhat
2012-06-01 9:10 ` [PATCH 02/27] smpboot: Add provisions for arch-specific locking around cpu_online_mask Srivatsa S. Bhat
2012-06-01 12:12 ` Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 04/27] smpboot, x86, xen: Determine smp booting implementations at run-time Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 05/27] xen, cpu hotplug: Don't call cpu_bringup() in xen_play_dead() Srivatsa S. Bhat
2012-06-01 12:59 ` [Xen-devel] " Jan Beulich
2012-06-01 15:13 ` Srivatsa S. Bhat
2012-06-01 15:36 ` Jan Beulich [this message]
2012-06-02 18:06 ` Srivatsa S. Bhat
2012-06-05 16:49 ` Konrad Rzeszutek Wilk
2012-06-05 17:36 ` Srivatsa S. Bhat
2012-06-05 17:40 ` Thomas Gleixner
2012-06-05 17:48 ` Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 06/27] xen, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:11 ` [PATCH 07/27] x86, " Srivatsa S. Bhat
2012-06-04 14:29 ` Thomas Gleixner
2012-06-04 17:00 ` Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 08/27] m32r: Fix horrible logic in smp_prepare_cpus() Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 09/27] m32r, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 10/27] mips, " Srivatsa S. Bhat
2012-06-03 8:25 ` Yong Zhang
2012-06-03 11:48 ` Srivatsa S. Bhat
2012-06-04 2:17 ` Yong Zhang
2012-06-01 9:12 ` [PATCH 11/27] sh, " Srivatsa S. Bhat
2012-06-01 9:12 ` [PATCH 12/27] tile, " Srivatsa S. Bhat
2012-06-01 18:07 ` Chris Metcalf
2012-06-01 9:13 ` [PATCH 13/27] hexagon, " Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 14/27] ia64: Move holding of vector_lock to __setup_vector_irq() Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 15/27] ia64, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:13 ` [PATCH 16/27] mn10300: Fix horrible logic in smp_prepare_cpus() Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 17/27] mn10300, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-03 8:33 ` Yong Zhang
2012-06-03 11:50 ` Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 18/27] powerpc, " Srivatsa S. Bhat
2012-06-02 6:14 ` Paul Mackerras
2012-06-01 9:14 ` [PATCH 19/27] blackfin, " Srivatsa S. Bhat
2012-06-01 9:14 ` [PATCH 20/27] sparc64, " Srivatsa S. Bhat
2012-06-01 17:55 ` David Miller
2012-06-01 22:44 ` [UPDATED PATCH " Srivatsa S. Bhat
2012-06-01 22:52 ` David Miller
2012-06-01 9:15 ` [PATCH 21/27] sparc32, " Srivatsa S. Bhat
2012-06-01 17:56 ` David Miller
2012-06-01 18:54 ` Sam Ravnborg
2012-06-01 22:47 ` [UPDATED PATCH " Srivatsa S. Bhat
2012-06-01 22:53 ` David Miller
2012-06-01 23:17 ` Srivatsa S. Bhat
2012-06-02 6:52 ` Sam Ravnborg
2012-06-02 7:44 ` Sam Ravnborg
2012-06-02 8:01 ` Srivatsa S. Bhat
2012-06-02 8:14 ` Srivatsa S. Bhat
2012-06-02 15:13 ` Sam Ravnborg
2012-06-02 15:58 ` Srivatsa S. Bhat
2012-06-02 16:23 ` Sam Ravnborg
2012-06-02 16:34 ` Srivatsa S. Bhat
2012-06-03 21:17 ` [PATCH] sparc32: refactor smp boot Sam Ravnborg
2012-06-04 1:04 ` David Miller
2012-06-04 6:48 ` Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 22/27] um, smpboot: Use generic SMP booting infrastructure Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 23/27] cris, " Srivatsa S. Bhat
2012-06-03 8:41 ` Yong Zhang
2012-06-03 11:52 ` Srivatsa S. Bhat
2012-06-01 9:15 ` [PATCH 24/27] parisc, " Srivatsa S. Bhat
2012-06-01 9:16 ` [PATCH 25/27] s390, " Srivatsa S. Bhat
2012-06-01 10:45 ` Heiko Carstens
2012-06-01 9:16 ` [PATCH 26/27] arm, " Srivatsa S. Bhat
2012-06-01 11:04 ` Russell King - ARM Linux
2012-06-01 9:16 ` [PATCH 27/27] alpha, " Srivatsa S. Bhat
[not found] ` <20120601091038.31979.67878.stgit@srivatsabhat.in.ibm.com>
2012-06-01 12:19 ` [PATCH 03/27] smpboot: Define and use cpu_state per-cpu variable in generic code Srivatsa S. Bhat
2012-06-01 12:25 ` Russell King - ARM Linux
2012-06-01 12:55 ` Srivatsa S. Bhat
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