From: Juergen Gross <jgross@suse.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
the arch/x86 maintainers <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
xen-devel <xen-devel@lists.xenproject.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
longman@redhat.com, mingo@redhat.com,
lkml <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH 1/2] xen: fix race in xen_qlock_wait()
Date: Mon, 1 Oct 2018 10:58:40 +0200 [thread overview]
Message-ID: <d75416af-2cc4-595a-48dc-381d14785191@suse.com> (raw)
On 01/10/2018 10:54, Jan Beulich wrote:
>>>> On 01.10.18 at 09:16, <jgross@suse.com> wrote:
>> In the following situation a vcpu waiting for a lock might not be
>> woken up from xen_poll_irq():
>>
>> CPU 1: CPU 2: CPU 3:
>> takes a spinlock
>> tries to get lock
>> -> xen_qlock_wait()
>> -> xen_clear_irq_pending()
>
> Doesn't the last line above ...
>
>> frees the lock
>> -> xen_qlock_kick(cpu2)
>
> ... need to be below here?
You are right, of course!
Thanks for noticing.
Juergen
next reply other threads:[~2018-10-01 8:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-01 8:58 Juergen Gross [this message]
-- strict thread matches above, loose matches on Subject: below --
2018-10-01 7:16 [PATCH 0/2] xen: fix two issues in Xen pv qspinlock handling Juergen Gross
2018-10-01 7:16 ` [PATCH 1/2] xen: fix race in xen_qlock_wait() Juergen Gross
2018-10-01 8:54 ` [Xen-devel] " Jan Beulich
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