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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, "K. Y. Srinivasan" <kys@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 054/177] netvsc: Deal with rescinded channels correctly
Date:   Fri, 23 Mar 2018 10:53:02 +0100
Message-Id: <20180323094207.738694716@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

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


[ Upstream commit 73e64fa4f417b22d8d5521999a631ced8e2d442e ]

We will not be able to send packets over a channel that has been
rescinded. Make necessary adjustments so we can properly cleanup
even when the channel is rescinded. This issue can be trigerred
in the NIC hot-remove path.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/hyperv/netvsc.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -151,6 +151,13 @@ static void netvsc_destroy_buf(struct hv
 				       sizeof(struct nvsp_message),
 				       (unsigned long)revoke_packet,
 				       VM_PKT_DATA_INBAND, 0);
+		/* If the failure is because the channel is rescinded;
+		 * ignore the failure since we cannot send on a rescinded
+		 * channel. This would allow us to properly cleanup
+		 * even when the channel is rescinded.
+		 */
+		if (device->channel->rescind)
+			ret = 0;
 		/*
 		 * If we failed here, we might as well return and
 		 * have a leak rather than continue and a bugchk
@@ -211,6 +218,15 @@ static void netvsc_destroy_buf(struct hv
 				       sizeof(struct nvsp_message),
 				       (unsigned long)revoke_packet,
 				       VM_PKT_DATA_INBAND, 0);
+
+		/* If the failure is because the channel is rescinded;
+		 * ignore the failure since we cannot send on a rescinded
+		 * channel. This would allow us to properly cleanup
+		 * even when the channel is rescinded.
+		 */
+		if (device->channel->rescind)
+			ret = 0;
+
 		/* If we failed here, we might as well return and
 		 * have a leak rather than continue and a bugchk
 		 */