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From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>, shuo.a.liu@intel.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Yu Wang <yu1.wang@intel.com>,
	Reinette Chatre <reinette.chatre@intel.com>,
	Yakui Zhao <yakui.zhao@intel.com>,
	Zhi Wang <zhi.a.wang@intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Fengwei Yin <fengwei.yin@intel.com>,
	Zhenyu Wang <zhenyuw@linux.intel.com>
Subject: Re: [PATCH v4 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler()
Date: Tue, 29 Sep 2020 22:07:17 +0200	[thread overview]
Message-ID: <873630jqiy.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200929175947.GL21110@zn.tnic>

On Tue, Sep 29 2020 at 20:01, Borislav Petkov wrote:
> On Tue, Sep 22, 2020 at 07:42:56PM +0800, shuo.a.liu@intel.com wrote:
>> +void acrn_setup_intr_handler(void (*handler)(void))
>> +{
>> +	acrn_intr_handler = handler;
>> +}
>> +EXPORT_SYMBOL_GPL(acrn_setup_intr_handler);
>> +
>> +void acrn_remove_intr_handler(void)
>> +{
>> +	acrn_intr_handler = NULL;
>> +}
>> +EXPORT_SYMBOL_GPL(acrn_remove_intr_handler);
>
> I don't like this one bit.
>
> Also, what stops the module from doing acrn_remove_intr_handler()
> while it gets a HYPERVISOR_CALLBACK_VECTOR interrupt and the handler
> disappearing from under it?
>
> IOW, this should be an atomic notifier instead.

That does not prevent that either and notifiers suck. The pointer is
fine and if something removes the handler before all of the muck is
shutdown then the author can keep the pieces and mop up the remains.

Thanks,

        tglx

  reply	other threads:[~2020-09-29 20:07 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-22 11:42 [PATCH v4 00/17] HSM driver for ACRN hypervisor shuo.a.liu
2020-09-22 11:42 ` [PATCH v4 01/17] docs: acrn: Introduce ACRN shuo.a.liu
2020-10-09  1:48   ` Randy Dunlap
2020-10-12  8:50     ` Shuo A Liu
2020-09-22 11:42 ` [PATCH v4 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr_handler() shuo.a.liu
2020-09-27 10:49   ` Greg Kroah-Hartman
2020-09-28  3:28     ` Shuo A Liu
2020-09-29 18:01   ` Borislav Petkov
2020-09-29 20:07     ` Thomas Gleixner [this message]
2020-09-29 20:26       ` Borislav Petkov
2020-09-30  3:02         ` Shuo A Liu
2020-09-22 11:42 ` [PATCH v4 03/17] x86/acrn: Introduce an API to check if a VM is privileged shuo.a.liu
2020-09-30  8:09   ` Borislav Petkov
2020-10-12  8:40     ` Shuo A Liu
2020-09-22 11:42 ` [PATCH v4 04/17] x86/acrn: Introduce hypercall interfaces shuo.a.liu
2020-09-27 10:51   ` Greg Kroah-Hartman
2020-09-27 10:53     ` Greg Kroah-Hartman
2020-09-28  3:38       ` Shuo A Liu
2020-09-27 15:38     ` Dave Hansen
2020-09-30 11:16       ` Peter Zijlstra
2020-09-30 16:10         ` Segher Boessenkool
2020-09-30 17:13           ` Peter Zijlstra
2020-09-30 19:14             ` Nick Desaulniers
2020-09-30 19:42               ` Peter Zijlstra
2020-09-30 23:58                 ` Segher Boessenkool
2020-09-30 19:59               ` Arvind Sankar
2020-09-30 20:01                 ` Arvind Sankar
2020-10-01  0:08                 ` Segher Boessenkool
2020-09-30 23:25               ` Segher Boessenkool
2020-09-30 23:38                 ` Arvind Sankar
2020-10-01  0:11                   ` Segher Boessenkool
2020-10-12  8:44               ` Shuo A Liu
2020-10-12 16:49                 ` Arvind Sankar
2020-10-13  2:44                   ` Shuo A Liu
2020-09-30 10:54   ` Borislav Petkov
2020-10-12  8:49     ` Shuo A Liu
2020-09-22 11:42 ` [PATCH v4 05/17] virt: acrn: Introduce ACRN HSM basic driver shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 08/17] virt: acrn: Introduce EPT mapping management shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 10/17] virt: acrn: Introduce PCI configuration space PIO accesses combiner shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 11/17] virt: acrn: Introduce interfaces for PCI device passthrough shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 12/17] virt: acrn: Introduce interrupt injection interfaces shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 14/17] virt: acrn: Introduce I/O ranges operation interfaces shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 16/17] virt: acrn: Introduce irqfd shuo.a.liu
2020-09-22 11:43 ` [PATCH v4 17/17] virt: acrn: Introduce an interface for Service VM to control vCPU shuo.a.liu
2020-09-27 10:44   ` Greg Kroah-Hartman
2020-09-28  4:10     ` Shuo A Liu
2020-09-28  5:23       ` Greg Kroah-Hartman
2020-09-28  6:33         ` Shuo A Liu
2020-09-27  0:24 ` [PATCH v4 00/17] HSM driver for ACRN hypervisor Liu, Shuo A
2020-09-27  5:42   ` Greg Kroah-Hartman
     [not found] ` <20200922114311.38804-7-shuo.a.liu@intel.com>
2020-09-27 10:45   ` [PATCH v4 06/17] virt: acrn: Introduce VM management interfaces Greg Kroah-Hartman
2020-09-28  3:43     ` Shuo A Liu
2020-09-27 10:47   ` Greg Kroah-Hartman
2020-09-28  3:50     ` Shuo A Liu
2020-09-28  5:25       ` Greg Kroah-Hartman
2020-09-28  6:29         ` Shuo A Liu
2020-09-28 12:26           ` Greg Kroah-Hartman
2020-09-30  2:49             ` Shuo A Liu

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