diff mbox series

[azure,4.13,15/19] Drivers: hv: vmbus: Fix a rescind issue

Message ID 1513093328-10999-16-git-send-email-marcelo.cerri@canonical.com
State New
Headers show
Series None | expand

Commit Message

Marcelo Henrique Cerri Dec. 12, 2017, 3:42 p.m. UTC 
From: K. Y. Srinivasan <kys@microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1736283

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since the channel is rescinded, the host will not respond and we could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: K. Y. Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from linux-next commit 7fa32e5ec28b1609abc0b797b58267f725fc3964)
Signed-off-by: Dexuan Cui <decui@microsoft.com>

Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
---
 drivers/hv/channel.c      | 10 ++++++++--
 drivers/hv/channel_mgmt.c |  7 ++++---
 include/linux/hyperv.h    |  1 +
 3 files changed, 13 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 82bbd9561050..2e2f5d02af80 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -655,22 +655,28 @@  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);
 }
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 19f374ce3658..fd5faa37d3cf 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -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);
@@ -894,6 +895,7 @@  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
@@ -909,7 +911,6 @@  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;
 		}
 		/*
@@ -918,7 +919,6 @@  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);
 		}
@@ -932,13 +932,14 @@  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);
 	}
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index f9088f52273d..822c7a3a4efc 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -720,6 +720,7 @@  struct vmbus_channel {
 	u8 monitor_bit;
 
 	bool rescind; /* got rescind msg */
+	struct completion rescind_event;
 
 	u32 ringbuffer_gpadlhandle;