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Subject[PATCH 1/2] Drivers: hv: vmbus: introduce vmbus_acpi_remove
Date
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 observed
when hv_vmbus unload/load sequence is performed on a 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 c85235e..0d8d1d7 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1035,6 +1035,15 @@ 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},
@@ -1047,6 +1056,7 @@ static struct acpi_driver vmbus_acpi_driver = {
.ids = vmbus_acpi_device_ids,
.ops = {
.add = vmbus_acpi_add,
+ .remove = vmbus_acpi_remove,
},
};

--
1.9.3


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