linux-kernel - RE: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi

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Date:	Fri, 10 Apr 2015 14:50:39 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Vitaly Kuznetsov <vkuznets@...hat.com>
CC:	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"Haiyang Zhang" <haiyangz@...rosoft.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dexuan Cui <decui@...rosoft.com>,
	Jake Oshins <jakeo@...rosoft.com>
Subject: RE: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove



> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> Sent: Friday, April 10, 2015 5:48 AM
> To: KY Srinivasan
> Cc: devel@...uxdriverproject.org; Haiyang Zhang; linux-
> kernel@...r.kernel.org; Dexuan Cui; Jake Oshins
> Subject: Re: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove
> 
> KY Srinivasan <kys@...rosoft.com> writes:
> 
> >> -----Original Message-----
> >> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
> >> Sent: Wednesday, January 21, 2015 11:02 AM
> >> To: KY Srinivasan; devel@...uxdriverproject.org
> >> Cc: Haiyang Zhang; linux-kernel@...r.kernel.org; Dexuan Cui
> >> Subject: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove
> >>
> >> In case we do request_resource() in vmbus_acpi_add() we need to tear it
> >> down to be able to load the driver again. Otherwise the following crash in
> >> oberved when hv_vmbus unload/load sequence is performed on
> >> Generation2 instance:
> >>
> >> [   38.165701] BUG: unable to handle kernel paging request at
> ffffffffa00075a0
> >> [   38.166315] IP: [<ffffffff8107dc5f>] __request_resource+0x2f/0x50
> >> [   38.166315] PGD 1f34067 PUD 1f35063 PMD 3f723067 PTE 0
> >> [   38.166315] Oops: 0000 [#1] SMP
> >> [   38.166315] Modules linked in: hv_vmbus(+) [last unloaded: hv_vmbus]
> >> [   38.166315] CPU: 0 PID: 267 Comm: modprobe Not tainted 3.19.0-
> >> rc5_bug923184+ #486
> >> [   38.166315] Hardware name: Microsoft Corporation Virtual
> Machine/Virtual
> >> Machine, BIOS Hyper-V UEFI Release v1.0 11/26/2012
> >> [   38.166315] task: ffff88003f401cb0 ti: ffff88003f60c000 task.ti:
> >> ffff88003f60c000
> >> [   38.166315] RIP: 0010:[<ffffffff8107dc5f>]  [<ffffffff8107dc5f>]
> >> __request_resource+0x2f/0x50
> >> [   38.166315] RSP: 0018:ffff88003f60fb58  EFLAGS: 00010286
> >> ...
> >>
> >> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> >> ---
> >>  drivers/hv/vmbus_drv.c | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index
> >> 4d6b269..b06cb87 100644
> >> --- a/drivers/hv/vmbus_drv.c
> >> +++ b/drivers/hv/vmbus_drv.c
> >> @@ -902,6 +902,15 @@ acpi_walk_err:
> >>  	return ret_val;
> >>  }
> >>
> >> +static int vmbus_acpi_remove(struct acpi_device *device) {
> >> +	int ret = 0;
> >> +
> >> +	if (hyperv_mmio.start && hyperv_mmio.end)
> >> +		ret = release_resource(&hyperv_mmio);
> >> +	return ret;
> >> +}
> >> +
> >>  static const struct acpi_device_id vmbus_acpi_device_ids[] = {
> >>  	{"VMBUS", 0},
> >>  	{"VMBus", 0},
> >> @@ -914,6 +923,7 @@ static struct acpi_driver vmbus_acpi_driver = {
> >>  	.ids = vmbus_acpi_device_ids,
> >>  	.ops = {
> >>  		.add = vmbus_acpi_add,
> >> +		.remove = vmbus_acpi_remove,
> >>  	},
> >>  };
> >
> > Vitaly,
> >
> > Jake has sent the following patch that has fixed retrieving of the mmio
> resources:
> > https://lkml.org/lkml/2015/1/20/876
> >
> > This patch also deals with the resource cleanup that you have in this patch.
> >
> 
> Hi K.Y.,
> 
> it looks like Jake was forced to redo his work, do you think it would
> make sense to have this simple fix for mainline in the meantime? I can
> rebase/resend in case you do.

Please do. Thanks.

K. Y
> 
> Thanks,
> 
> --
>   Vitaly
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