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Subject: Re: [PATCH 0/2] xen: fix two issues in Xen pv qspinlock handling
To:     David Woodhouse <dwmw2@infradead.org>,
        linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
        x86@kernel.org
Cc:     boris.ostrovsky@oracle.com, hpa@zytor.com, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, Waiman.Long@hp.com,
        peterz@infradead.org
References: <20181001071641.19282-1-jgross@suse.com>
 <762802a4b8ff21e43e59e222e472ab9b23fc43cd.camel@infradead.org>
From:   Juergen Gross <jgross@suse.com>
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Date:   Tue, 9 Oct 2018 16:52:28 +0200
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On 09/10/2018 16:40, David Woodhouse wrote:
> On Mon, 2018-10-01 at 09:16 +0200, Juergen Gross wrote:
>> The Xen specific queue spinlock wait function has two issues which
>> could result in a hanging system.
>>
>> They have a similar root cause of clearing a pending wakeup of a
>> waiting vcpu and later going to sleep waiting for the just cleared
>> wakeup event, which of course won't ever happen.
>>
>> Juergen Gross (2):
>>   xen: fix race in xen_qlock_wait()
>>   xen: make xen_qlock_wait() nestable
>>
>>  arch/x86/xen/spinlock.c | 33 ++++++++++++---------------------
>>  1 file changed, 12 insertions(+), 21 deletions(-)
>>
>> Cc: Waiman.Long@hp.com
>> Cc: peterz@infradead.org
> 
> LGTM. Both these should be Cc:stable@vger.kernel.org, yes?

Yes, they are.

I have them already queued in the Xen tree. As the bug is rather
old I didn't want to rush the patches in so late in the rc phase of
4.19.


Juergen