We need to destroy hv_vmbus_con on module shutdown, otherwise the following
crash is sometimes observed:
[ 76.569845] hv_vmbus: Hyper-V Host Build:9600-6.3-17-0.17039; Vmbus version:3.0
[ 82.598859] BUG: unable to handle kernel paging request at ffffffffa0003480
[ 82.599287] IP: [<ffffffffa0003480>] 0xffffffffa0003480
[ 82.599287] PGD 1f34067 PUD 1f35063 PMD 3f72d067 PTE 0
[ 82.599287] Oops: 0010 [#1] SMP
[ 82.599287] Modules linked in: [last unloaded: hv_vmbus]
[ 82.599287] CPU: 0 PID: 26 Comm: kworker/0:1 Not tainted 3.19.0-rc5_bug923184+ #488
[ 82.599287] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v1.0 11/26/2012
[ 82.599287] Workqueue: hv_vmbus_con 0xffffffffa0003480
[ 82.599287] task: ffff88007b6ddfa0 ti: ffff88007f8f8000 task.ti: ffff88007f8f8000
[ 82.599287] RIP: 0010:[<ffffffffa0003480>] [<ffffffffa0003480>] 0xffffffffa0003480
[ 82.599287] RSP: 0018:ffff88007f8fbe00 EFLAGS: 00010202
...
To avoid memory leaks we need to free monitor_pages and int_page for
vmbus_connection. Implement vmbus_disconnect() function by separating cleanup
path from vmbus_connect().
As we use hv_vmbus_con to release channels (see free_channel() in channel_mgmt.c)
we need to make sure the work was done before we remove the queue, do that with
drain_workqueue(). We also need to avoid handling messages which can (potentially)
create new channels, so set vmbus_connection.conn_state = DISCONNECTED at the very
beginning of vmbus_exit() and check for that in vmbus_onmessage_work().
Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
drivers/hv/connection.c | 17 ++++++++++++-----
drivers/hv/hyperv_vmbus.h | 1 +
drivers/hv/vmbus_drv.c | 6 ++++++
3 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index e206619..2fce0c7 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -214,10 +214,21 @@ int vmbus_connect(void)
cleanup:
pr_err("Unable to connect to host\n");
+
vmbus_connection.conn_state = DISCONNECTED;
+ vmbus_disconnect();
+
+ kfree(msginfo);
+
+ return ret;
+}
- if (vmbus_connection.work_queue)
+void vmbus_disconnect(void)
+{
+ if (vmbus_connection.work_queue) {
+ drain_workqueue(vmbus_connection.work_queue);
destroy_workqueue(vmbus_connection.work_queue);
+ }
if (vmbus_connection.int_page) {
free_pages((unsigned long)vmbus_connection.int_page, 0);
@@ -228,10 +239,6 @@ cleanup:
free_pages((unsigned long)vmbus_connection.monitor_pages[1], 0);
vmbus_connection.monitor_pages[0] = NULL;
vmbus_connection.monitor_pages[1] = NULL;
-
- kfree(msginfo);
-
- return ret;
}
/*
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index c386d8d..e01c13e 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -671,6 +671,7 @@ void vmbus_free_channels(void);
/* Connection interface */
int vmbus_connect(void);
+void vmbus_disconnect(void);
int vmbus_post_msg(void *buffer, size_t buflen);
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index b06cb87..e647505 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -572,6 +572,10 @@ static void vmbus_onmessage_work(struct work_struct *work)
{
struct onmessage_work_context *ctx;
+ /* Do not process messages if we're in DISCONNECTED state */
+ if (vmbus_connection.conn_state == DISCONNECTED)
+ return;
+
ctx = container_of(work, struct onmessage_work_context,
work);
vmbus_onmessage(&ctx->msg);
@@ -969,11 +973,13 @@ cleanup:
static void __exit vmbus_exit(void)
{
+ vmbus_connection.conn_state = DISCONNECTED;
hv_remove_vmbus_irq();
vmbus_free_channels();
bus_unregister(&hv_bus);
hv_cleanup();
acpi_bus_unregister_driver(&vmbus_acpi_driver);
+ vmbus_disconnect();
}
--
1.9.3
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