RE: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove

[KY Srinivasan <kys@microsoft.com>]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Wednesday, January 21, 2015 11:02 AM
> To: KY Srinivasan; devel@linuxdriverproject.org
> Cc: Haiyang Zhang; linux-kernel@vger.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@redhat.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.

Regards,

K. Y
> 
> --
> 1.9.3