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


> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com]
> Sent: Friday, April 10, 2015 5:48 AM
> To: KY Srinivasan
> Cc: devel@linuxdriverproject.org; Haiyang Zhang; linux-
> kernel@vger.kernel.org; Dexuan Cui; Jake Oshins
> Subject: Re: [PATCH 2/3] Drivers: hv: vmbus: introduce vmbus_acpi_remove
>
> KY Srinivasan <kys@microsoft.com> writes:
>
> >> -----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.
> >
>
> 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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