Patch "Drivers: hv: vmbus: Fix a rescind issue" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Drivers: hv: vmbus: Fix a rescind issue

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drivers-hv-vmbus-fix-a-rescind-issue.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7fa32e5ec28b1609abc0b797b58267f725fc3964 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Tue, 14 Nov 2017 06:53:33 -0700
Subject: Drivers: hv: vmbus: Fix a rescind issue

From: K. Y. Srinivasan <kys@microsoft.com>

commit 7fa32e5ec28b1609abc0b797b58267f725fc3964 upstream.

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since the channel is rescinded, the host will not respond and we could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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hv/channel.c      |   10 ++++++++--
 drivers/hv/channel_mgmt.c |    7 ++++---
 include/linux/hyperv.h    |    1 +
 3 files changed, 13 insertions(+), 5 deletions(-)

--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -640,22 +640,28 @@ void vmbus_close(struct vmbus_channel *c
 		 */
 		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);
 }
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -333,6 +333,7 @@ static struct vmbus_channel *alloc_chann
 		return NULL;
 
 	spin_lock_init(&channel->lock);
+	init_completion(&channel->rescind_event);
 
 	INIT_LIST_HEAD(&channel->sc_list);
 	INIT_LIST_HEAD(&channel->percpu_list);
@@ -883,6 +884,7 @@ static void vmbus_onoffer_rescind(struct
 	/*
 	 * 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
@@ -898,7 +900,6 @@ static void vmbus_onoffer_rescind(struct
 	if (channel->device_obj) {
 		if (channel->chn_rescind_callback) {
 			channel->chn_rescind_callback(channel);
-			vmbus_rescind_cleanup(channel);
 			return;
 		}
 		/*
@@ -907,7 +908,6 @@ static void vmbus_onoffer_rescind(struct
 		 */
 		dev = get_device(&channel->device_obj->device);
 		if (dev) {
-			vmbus_rescind_cleanup(channel);
 			vmbus_device_unregister(channel->device_obj);
 			put_device(dev);
 		}
@@ -921,13 +921,14 @@ static void vmbus_onoffer_rescind(struct
 		 * 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);
 	}
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -708,6 +708,7 @@ struct vmbus_channel {
 	u8 monitor_bit;
 
 	bool rescind; /* got rescind msg */
+	struct completion rescind_event;
 
 	u32 ringbuffer_gpadlhandle;
 


Patches currently in stable-queue which might be from kys@microsoft.com are

queue-4.14/hv-kvp-avoid-reading-past-allocated-blocks-from-kvp-file.patch
queue-4.14/drivers-hv-vmbus-fix-a-rescind-issue.patch