From 9d35593b4f0b89ab0c194349c7d357b3b159e99a Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Wed, 18 Oct 2017 02:08:40 -0700 Subject: [PATCH] vmbus: hvsock: add proper sync for vmbus_hvsock_device_unregister() Without the patch, vmbus_hvsock_device_unregister() can destroy the device prematurely when close() is called, and can cause NULl dereferencing or potential data loss (the last portion of the data stream may be dropped prematurely). Signed-off-by: Dexuan Cui Cc: Haiyang Zhang Cc: Stephen Hemminger Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 018d2e0f8ec5..379b0df123be 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -937,7 +937,10 @@ void vmbus_hvsock_device_unregister(struct vmbus_channel *channel) { BUG_ON(!is_hvsock_channel(channel)); - channel->rescind = true; + /* We always get a rescind msg when a connection is closed. */ + while (!READ_ONCE(channel->probe_done) || !READ_ONCE(channel->rescind)) + msleep(1); + vmbus_device_unregister(channel->device_obj); } EXPORT_SYMBOL_GPL(vmbus_hvsock_device_unregister); -- 2.20.1