[3.8.y.z extended stable] Patch "Drivers: hv: vmbus: Don't timeout during the initial connection with" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Drivers: hv: vmbus: Don't timeout during the initial connection with

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From faca44e2f6d2b97a0ae01ae6ca68ac5b34a98df3 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys at microsoft.com>
Date: Thu, 16 Jan 2014 11:59:58 -0800
Subject: Drivers: hv: vmbus: Don't timeout during the initial connection with
 host

commit 269f979467cf49f2ea8132316c1f00f8c9678f7c upstream.

When the guest attempts to connect with the host when there may already be a
connection with the host (as would be the case during the kdump/kexec path),
it is difficult to guarantee timely response from the host. Starting with
WS2012 R2, the host supports this ability to re-connect with the host
(explicitly to support kexec). Prior to responding to the guest, the host
needs to ensure that device states based on the previous connection to
the host have been properly torn down. This may introduce unbounded delays.
To deal with this issue, don't do a timed wait during the initial connect
with the host.

Signed-off-by: K. Y. Srinivasan <kys at microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
[ kamal: backport to 3.8 (applied to vmbus_connect) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/hv/connection.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 650c9f0..d7f3df9 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -45,7 +45,6 @@ struct vmbus_connection vmbus_connection = {
 int vmbus_connect(void)
 {
 	int ret = 0;
-	int t;
 	struct vmbus_channel_msginfo *msginfo = NULL;
 	struct vmbus_channel_initiate_contact *msg;
 	unsigned long flags;
@@ -132,16 +131,7 @@ int vmbus_connect(void)
 	}

 	/* Wait for the connection response */
-	t =  wait_for_completion_timeout(&msginfo->waitevent, 5*HZ);
-	if (t == 0) {
-		spin_lock_irqsave(&vmbus_connection.channelmsg_lock,
-				flags);
-		list_del(&msginfo->msglistentry);
-		spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock,
-					flags);
-		ret = -ETIMEDOUT;
-		goto cleanup;
-	}
+	wait_for_completion(&msginfo->waitevent);

 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 	list_del(&msginfo->msglistentry);
--
1.8.3.2