linux-kernel - [PATCH v2,1/1] net/hyperv: Fix the code handling tx busy

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Message-Id: <1332192233-32305-2-git-send-email-haiyangz@microsoft.com>
Date:	Mon, 19 Mar 2012 14:23:53 -0700
From:	Haiyang Zhang <haiyangz@...rosoft.com>
To:	haiyangz@...rosoft.com, kys@...rosoft.com, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	devel@...uxdriverproject.org
Subject: [PATCH v2,1/1] net/hyperv: Fix the code handling tx busy

Instead of dropping the packet, we keep the skb buffer, and return
NETDEV_TX_BUSY to let upper layer retry send. This will not cause
endless loop, because the host is taking data away from ring buffer,
and we have called the stop_queue before returning NETDEV_TX_BUSY.

The stop_queue was called in the function netvsc_send() in file 
netvsc.c, then it returns to rndis_filter_send(), which returns to
netvsc_start_xmit() in file netvsc_drv.c. So the NETDEV_TX_BUSY is
indeed returned AFTER queue is stopped.

Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
Reviewed-by: K. Y. Srinivasan <kys@...rosoft.com>
---
 drivers/net/hyperv/netvsc_drv.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 2517d20..dd29478 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -223,13 +223,10 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 		net->stats.tx_bytes += skb->len;
 		net->stats.tx_packets++;
 	} else {
-		/* we are shutting down or bus overloaded, just drop packet */
-		net->stats.tx_dropped++;
 		kfree(packet);
-		dev_kfree_skb_any(skb);
 	}
 
-	return NETDEV_TX_OK;
+	return ret ? NETDEV_TX_BUSY : NETDEV_TX_OK;
 }
 
 /*
-- 
1.7.4.1

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