diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2014-11-04 13:40:11 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-01-16 06:59:32 -0800 |
| commit | 8a8c38c8e681f36170d6d565c8c50539f7845667 (patch) | |
| tree | eb0f7cad75100a296063e9c6b3fbef09d2294004 | |
| parent | 7810e6d8f1390a96e634e66072064c69a6f7d08d (diff) | |
Drivers: hv: vmbus: Fix a race condition when unregistering a device
commit 04a258c162a85c0f4ae56be67634dc43c9a4fa9b upstream.
When build with Debug the following crash is sometimes observed:
Call Trace:
[<ffffffff812b9600>] string+0x40/0x100
[<ffffffff812bb038>] vsnprintf+0x218/0x5e0
[<ffffffff810baf7d>] ? trace_hardirqs_off+0xd/0x10
[<ffffffff812bb4c1>] vscnprintf+0x11/0x30
[<ffffffff8107a2f0>] vprintk+0xd0/0x5c0
[<ffffffffa0051ea0>] ? vmbus_process_rescind_offer+0x0/0x110 [hv_vmbus]
[<ffffffff8155c71c>] printk+0x41/0x45
[<ffffffffa004ebac>] vmbus_device_unregister+0x2c/0x40 [hv_vmbus]
[<ffffffffa0051ecb>] vmbus_process_rescind_offer+0x2b/0x110 [hv_vmbus]
...
This happens due to the following race: between 'if (channel->device_obj)' check
in vmbus_process_rescind_offer() and pr_debug() in vmbus_device_unregister() the
device can disappear. Fix the issue by taking an additional reference to the
device before proceeding to vmbus_device_unregister().
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/hv/channel_mgmt.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index fa920469bf10..505fe29c75b0 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -202,9 +202,16 @@ static void vmbus_process_rescind_offer(struct work_struct *work) unsigned long flags; struct vmbus_channel *primary_channel; struct vmbus_channel_relid_released msg; + struct device *dev; + + if (channel->device_obj) { + dev = get_device(&channel->device_obj->device); + if (dev) { + vmbus_device_unregister(channel->device_obj); + put_device(dev); + } + } - if (channel->device_obj) - vmbus_device_unregister(channel->device_obj); memset(&msg, 0, sizeof(struct vmbus_channel_relid_released)); msg.child_relid = channel->offermsg.child_relid; msg.header.msgtype = CHANNELMSG_RELID_RELEASED; |