linux-kernel - [PATCH 05/21] Drivers: hv: vss: process deferred messages when we complete the transaction

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Date:	Sat, 11 Apr 2015 18:07:43 -0700
From:	"K. Y. Srinivasan" <kys@...rosoft.com>
To:	gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org, olaf@...fle.de, apw@...onical.com,
	vkuznets@...hat.com, jasowang@...hat.com
Cc:	"K. Y. Srinivasan" <kys@...rosoft.com>
Subject: [PATCH 05/21] Drivers: hv: vss: process deferred messages when we complete the transaction

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

In theory, the host is not supposed to issue any requests before be reply to
the previous one. In KVP we, however, support the following scenarios:
1) A message was received before userspace daemon registered;
2) A message was received while the previous one is still being processed.
In VSS we support only the former. Add support for the later, use
hv_poll_channel() to do the job.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Tested-by: Alex Ng <alexng@...rosoft.com>
Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
---
 drivers/hv/hv_snapshot.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index c1a3604..4bb9b1c 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -47,6 +47,7 @@ static struct {
 	struct vmbus_channel *recv_channel; /* chn we got the request */
 	u64 recv_req_id; /* request ID. */
 	struct hv_vss_msg  *msg; /* current message */
+	void *vss_context; /* for the channel callback */
 } vss_transaction;
 
 
@@ -73,6 +74,9 @@ static void vss_timeout_func(struct work_struct *dummy)
 	 */
 	pr_warn("VSS: timeout waiting for daemon to reply\n");
 	vss_respond_to_host(HV_E_FAIL);
+
+	hv_poll_channel(vss_transaction.vss_context,
+			hv_vss_onchannelcallback);
 }
 
 static void
@@ -85,13 +89,12 @@ vss_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
 	if (vss_msg->vss_hdr.operation == VSS_OP_REGISTER) {
 		pr_info("VSS daemon registered\n");
 		vss_transaction.active = false;
-		if (vss_transaction.recv_channel != NULL)
-			hv_vss_onchannelcallback(vss_transaction.recv_channel);
-		return;
-
 	}
 	if (cancel_delayed_work_sync(&vss_timeout_work))
 		vss_respond_to_host(vss_msg->error);
+
+	hv_poll_channel(vss_transaction.vss_context,
+			hv_vss_onchannelcallback);
 }
 
 
@@ -198,9 +201,10 @@ void hv_vss_onchannelcallback(void *context)
 		 * We will defer processing this callback once
 		 * the current transaction is complete.
 		 */
-		vss_transaction.recv_channel = channel;
+		vss_transaction.vss_context = context;
 		return;
 	}
+	vss_transaction.vss_context = NULL;
 
 	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
 			 &requestid);
-- 
1.7.4.1

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