linux-kernel - [PATCH 4.4 10/28] Drivers: hv: get rid of timeout in vmbus

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Date:   Tue, 25 Apr 2017 16:08:41 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Sumit Semwal <sumit.semwal@...aro.org>
Subject: [PATCH 4.4 10/28] Drivers: hv: get rid of timeout in vmbus_open()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vitaly Kuznetsov <vkuznets@...hat.com>

commit 396e287fa2ff46e83ae016cdcb300c3faa3b02f6 upstream.

vmbus_teardown_gpadl() can result in infinite wait when it is called on 5
second timeout in vmbus_open(). The issue is caused by the fact that gpadl
teardown operation won't ever succeed for an opened channel and the timeout
isn't always enough. As a guest, we can always trust the host to respond to
our request (and there is nothing we can do if it doesn't).

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
Signed-off-by: Sumit Semwal <sumit.semwal@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/hv/channel.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -73,7 +73,6 @@ int vmbus_open(struct vmbus_channel *new
 	void *in, *out;
 	unsigned long flags;
 	int ret, err = 0;
-	unsigned long t;
 	struct page *page;

 	spin_lock_irqsave(&newchannel->lock, flags);
@@ -183,11 +182,7 @@ int vmbus_open(struct vmbus_channel *new
 		goto error1;
 	}

-	t = wait_for_completion_timeout(&open_info->waitevent, 5*HZ);
-	if (t == 0) {
-		err = -ETIMEDOUT;
-		goto error1;
-	}
+	wait_for_completion(&open_info->waitevent);

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