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Commit 7fa32e5e authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
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Drivers: hv: vmbus: Fix a rescind issue 



The current rescind processing code will not correctly handle
the case where the host immediately rescinds a channel that has
been offerred. In this case, we could be blocked in the open call and
since the channel is rescinded, the host will not respond and we could
be blocked forever in the vmbus open call.i Fix this problem.

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fb2c4452

drivers/hv/channel.c

+8 −2
Original line number Diff line number Diff line
@@ -659,22 +659,28 @@ void vmbus_close(struct vmbus_channel *channel) 
		 */

		return;

	}

	mutex_lock(&vmbus_connection.channel_mutex);

	/*

	 * Close all the sub-channels first and then close the

	 * primary channel.

	 */

	list_for_each_safe(cur, tmp, &channel->sc_list) {

		cur_channel = list_entry(cur, struct vmbus_channel, sc_list);

		vmbus_close_internal(cur_channel);

		if (cur_channel->rescind) {

			wait_for_completion(&cur_channel->rescind_event);

			mutex_lock(&vmbus_connection.channel_mutex);

			vmbus_close_internal(cur_channel);

			hv_process_channel_removal(

					   cur_channel->offermsg.child_relid);

		} else {

			mutex_lock(&vmbus_connection.channel_mutex);

			vmbus_close_internal(cur_channel);

		}

		mutex_unlock(&vmbus_connection.channel_mutex);

	}

	/*

	 * Now close the primary.

	 */

	mutex_lock(&vmbus_connection.channel_mutex);

	vmbus_close_internal(channel);

	mutex_unlock(&vmbus_connection.channel_mutex);

}

drivers/hv/channel_mgmt.c

+4 −3
Original line number Diff line number Diff line
@@ -333,6 +333,7 @@ static struct vmbus_channel *alloc_channel(void) 
		return NULL;



	spin_lock_init(&channel->lock);

	init_completion(&channel->rescind_event);



	INIT_LIST_HEAD(&channel->sc_list);

	INIT_LIST_HEAD(&channel->percpu_list);
@@ -898,6 +899,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
	/*

	 * Now wait for offer handling to complete.

	 */

	vmbus_rescind_cleanup(channel);

	while (READ_ONCE(channel->probe_done) == false) {

		/*

		 * We wait here until any channel offer is currently
@@ -913,7 +915,6 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
	if (channel->device_obj) {

		if (channel->chn_rescind_callback) {

			channel->chn_rescind_callback(channel);

			vmbus_rescind_cleanup(channel);

			return;

		}

		/*
@@ -922,7 +923,6 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
		 */

		dev = get_device(&channel->device_obj->device);

		if (dev) {

			vmbus_rescind_cleanup(channel);

			vmbus_device_unregister(channel->device_obj);

			put_device(dev);

		}
@@ -936,13 +936,14 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) 
		 * 2. Then close the primary channel.

		 */

		mutex_lock(&vmbus_connection.channel_mutex);

		vmbus_rescind_cleanup(channel);

		if (channel->state == CHANNEL_OPEN_STATE) {

			/*

			 * The channel is currently not open;

			 * it is safe for us to cleanup the channel.

			 */

			hv_process_channel_removal(rescind->child_relid);

		} else {

			complete(&channel->rescind_event);

		}

		mutex_unlock(&vmbus_connection.channel_mutex);

	}

include/linux/hyperv.h

+1 −0
Original line number Diff line number Diff line
@@ -708,6 +708,7 @@ struct vmbus_channel { 
	u8 monitor_bit;



	bool rescind; /* got rescind msg */

	struct completion rescind_event;



	u32 ringbuffer_gpadlhandle;