linux-kernel - RE: [PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for tearing down vmbus state

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Date:	Mon, 20 Apr 2015 14:32:36 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Vitaly Kuznetsov <vkuznets@...hat.com>
CC:	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"apw@...onical.com" <apw@...onical.com>,
	"jasowang@...hat.com" <jasowang@...hat.com>
Subject: RE: [PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for
 tearing down vmbus state



> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> Sent: Monday, April 20, 2015 7:17 AM
> To: KY Srinivasan
> Cc: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;
> devel@...uxdriverproject.org; olaf@...fle.de; apw@...onical.com;
> jasowang@...hat.com
> Subject: Re: [PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for
> tearing down vmbus state
> 
> KY Srinivasan <kys@...rosoft.com> writes:
> 
> >> -----Original Message-----
> >> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> >> Sent: Monday, April 20, 2015 2:40 AM
> >> To: KY Srinivasan
> >> Cc: gregkh@...uxfoundation.org; linux-kernel@...r.kernel.org;
> >> devel@...uxdriverproject.org; olaf@...fle.de; apw@...onical.com;
> >> jasowang@...hat.com
> >> Subject: Re: [PATCH 5/5] Drivers: hv: vmbus: Implement the protocol for
> >> tearing down vmbus state
> >>
> >> "K. Y. Srinivasan" <kys@...rosoft.com> writes:
> >>
> >> > Implement the protocol for tearing down the monitor state established
> >> with
> >> > the host.
> >> >
> >> > Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> >>
> >> Unfortunatelly this patch leads to the following crash:
> >
> > Thanks for testing Vitaly. The unload handling is what we want, maybe I
> need to
> > Invoke unload a little earlier.
> 
> I actually sent two letters this morning :-) The other was:
> 
> The problem is that we call vmbus_disconnect() too late in
> vmbus_exit(). We need to call it:
> 1) Before hv_cleanup() call as we free hypercall page there (that's what
> you see in my crash)
> 2) Before hv_remove_vmbus_irq() as we're waiting for the hypervisor to
> reply.
> 
> This simple patch fixes the issue:
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 7870a90..2b56260 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -1106,6 +1106,7 @@ static void __exit vmbus_exit(void)
> 
>         vmbus_connection.conn_state = DISCONNECTED;
>         hv_synic_clockevents_cleanup();
> +       vmbus_disconnect();
>         hv_remove_vmbus_irq();
>         vmbus_free_channels();
>         if (ms_hyperv.features &
> HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE) {
> @@ -1118,7 +1119,6 @@ static void __exit vmbus_exit(void)
>                 smp_call_function_single(cpu, hv_synic_cleanup, NULL,
>         1);
>         acpi_bus_unregister_driver(&vmbus_acpi_driver);
>         hv_cpu_hotplug_quirk(false);
> -       vmbus_disconnect();
>  }
> 
> I suggest we incorporate it into your PATCH 5/5.

Thank you; I will resend the patch with your fix.

Regards,

K. Y
> 
> --
>   Vitaly
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