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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Stephen Hemminger <sthemmin@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 021/165] hv_netvsc: avoid retry on send during shutdown
Date:   Thu, 24 May 2018 11:37:07 +0200
Message-Id: <20180524093622.835733732@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Stephen Hemminger <stephen@networkplumber.org>

[ Commit 12f69661a49446840d742d8feb593ace022d9f66 upstream. ]

Change the initialization order so that the device is ready to transmit
(ie connect vsp is completed) before setting the internal reference
to the device with RCU.

This avoids any races on initialization and prevents retry issues
on shutdown.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/hyperv/netvsc.c |   24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -850,13 +850,6 @@ int netvsc_send(struct net_device *ndev,
 	if (unlikely(!net_device || net_device->destroy))
 		return -ENODEV;
 
-	/* We may race with netvsc_connect_vsp()/netvsc_init_buf() and get
-	 * here before the negotiation with the host is finished and
-	 * send_section_map may not be allocated yet.
-	 */
-	if (unlikely(!net_device->send_section_map))
-		return -EAGAIN;
-
 	nvchan = &net_device->chan_table[packet->q_idx];
 	packet->send_buf_index = NETVSC_INVALID_INDEX;
 	packet->cp_partial = false;
@@ -864,10 +857,8 @@ int netvsc_send(struct net_device *ndev,
 	/* Send control message directly without accessing msd (Multi-Send
 	 * Data) field which may be changed during data packet processing.
 	 */
-	if (!skb) {
-		cur_send = packet;
-		goto send_now;
-	}
+	if (!skb)
+		return netvsc_send_pkt(device, packet, net_device, pb, skb);
 
 	/* batch packets in send buffer if possible */
 	msdp = &nvchan->msd;
@@ -951,7 +942,6 @@ int netvsc_send(struct net_device *ndev,
 		}
 	}
 
-send_now:
 	if (cur_send)
 		ret = netvsc_send_pkt(device, cur_send, net_device, pb, skb);
 
@@ -1308,11 +1298,6 @@ struct netvsc_device *netvsc_device_add(
 
 	napi_enable(&net_device->chan_table[0].napi);
 
-	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
-	 * populated.
-	 */
-	rcu_assign_pointer(net_device_ctx->nvdev, net_device);
-
 	/* Connect with the NetVsp */
 	ret = netvsc_connect_vsp(device, net_device, device_info);
 	if (ret != 0) {
@@ -1321,6 +1306,11 @@ struct netvsc_device *netvsc_device_add(
 		goto close;
 	}
 
+	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
+	 * populated.
+	 */
+	rcu_assign_pointer(net_device_ctx->nvdev, net_device);
+
 	return net_device;
 
 close: