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

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Message-Id: <1421866929-20167-3-git-send-email-vkuznets@redhat.com>
Date:	Wed, 21 Jan 2015 20:02:08 +0100
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	"K. Y. Srinivasan" <kys@...rosoft.com>,
	devel@...uxdriverproject.org
Cc:	Haiyang Zhang <haiyangz@...rosoft.com>,
	linux-kernel@...r.kernel.org, Dexuan Cui <decui@...rosoft.com>
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,
 	},
 };
 
-- 
1.9.3

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