linux-kernel - [PATCH 3.16 161/233] net: ethoc: enable NAPI before poll may be scheduled

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Date:   Sat, 09 Sep 2017 22:47:15 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David S. Miller" <davem@...emloft.net>,
        "Max Filippov" <jcmvbkbc@...il.com>,
        "Florian Fainelli" <f.fainelli@...il.com>,
        "Tobias Klauser" <tklauser@...tanz.ch>
Subject: [PATCH 3.16 161/233] net: ethoc: enable NAPI before poll may be
 scheduled

3.16.48-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Max Filippov <jcmvbkbc@...il.com>

commit d220b942a4b6a0640aee78841608f4aa5e8e185e upstream.

ethoc_reset enables device interrupts, ethoc_interrupt may schedule a
NAPI poll before NAPI is enabled in the ethoc_open, which results in
device being unable to send or receive anything until it's closed and
reopened. In case the device is flooded with ingress packets it may be
unable to recover at all.
Move napi_enable above ethoc_reset in the ethoc_open to fix that.

Fixes: a1702857724f ("net: Add support for the OpenCores 10/100 Mbps Ethernet MAC.")
Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
Reviewed-by: Tobias Klauser <tklauser@...tanz.ch>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/net/ethernet/ethoc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/ethoc.c
+++ b/drivers/net/ethernet/ethoc.c
@@ -706,6 +706,8 @@ static int ethoc_open(struct net_device
 	if (ret)
 		return ret;
 
+	napi_enable(&priv->napi);
+
 	ethoc_init_ring(priv, dev->mem_start);
 	ethoc_reset(priv);
 
@@ -718,7 +720,6 @@ static int ethoc_open(struct net_device
 	}
 
 	phy_start(priv->phy);
-	napi_enable(&priv->napi);
 
 	if (netif_msg_ifup(priv)) {
 		dev_info(&dev->dev, "I/O: %08lx Memory: %08lx-%08lx\n",