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

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Date:	Fri, 10 Apr 2015 14:47:57 +0200
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	KY Srinivasan <kys@...rosoft.com>
Cc:	"devel\@linuxdriverproject.org" <devel@...uxdriverproject.org>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"linux-kernel\@vger.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

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.

Thanks,

-- 
  Vitaly
--
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