From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Yanmin Zhang <yanmin_zhang@linux.intel.com>,
Joerg Roedel <jroedel@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>, Peter Anvin <hpa@zytor.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Borislav Petkov <bp@suse.de>, xiao jin <jin.xiao@intel.com>
Subject: Re: [patch 1/4] hotplug: Prevent alloc/free of irq descriptors during cpu up/down
Date: Tue, 14 Jul 2015 12:03:14 -0400 [thread overview]
Message-ID: <55A532C2.4080306__29572.6712247872$1436889931$gmane$org@oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1507141743150.18576@nanos>
On 07/14/2015 11:44 AM, Thomas Gleixner wrote:
> On Tue, 14 Jul 2015, Boris Ostrovsky wrote:
>>> Prevent allocation and freeing of interrupt descriptors accross cpu
>>> hotplug.
>>
>> This breaks Xen guests that allocate interrupt descriptors in .cpu_up().
> And where exactly does XEN allocate those descriptors?
xen_cpu_up()
xen_setup_timer()
bind_virq_to_irqhandler()
bind_virq_to_irq()
xen_allocate_irq_dynamic()
xen_allocate_irqs_dynamic()
irq_alloc_descs()
There is also a similar pass via xen_cpu_up() -> xen_smp_intr_init()
>
>> Any chance this locking can be moved into arch code?
> No.
>
>> (The patch doesn't appear to have any side effects for the down path since Xen
>> guests deallocate descriptors in __cpu_die()).
>
> Exact place please.
Whose place? Where descriptors are deallocated?
__cpu_die()
xen_cpu_die()
xen_teardown_timer()
unbind_from_irqhandler()
unbind_from_irq()
__unbind_from_irq()
xen_free_irq()
irq_free_descs()
free_desc()
-boris
next prev parent reply other threads:[~2015-07-14 16:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20150705170530.849428850@linutronix.de>
[not found] ` <20150705171102.063519515@linutronix.de>
2015-07-14 14:39 ` [patch 1/4] hotplug: Prevent alloc/free of irq descriptors during cpu up/down Boris Ostrovsky
[not found] ` <55A51F10.7010407@oracle.com>
2015-07-14 15:44 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.11.1507141743150.18576@nanos>
2015-07-14 16:03 ` Boris Ostrovsky [this message]
[not found] ` <55A532C2.4080306@oracle.com>
2015-07-14 17:32 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.11.1507141901460.18576@nanos>
2015-07-14 20:04 ` Boris Ostrovsky
[not found] ` <55A56B48.4060605@oracle.com>
2015-07-14 20:15 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.11.1507142211390.18576@nanos>
2015-07-14 21:07 ` Boris Ostrovsky
[not found] ` <55A579FD.6030000@oracle.com>
2016-03-12 9:19 ` Thomas Gleixner
[not found] ` <alpine.DEB.2.11.1603121017500.3657@nanos>
2016-03-14 13:12 ` Boris Ostrovsky
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