From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 18 Feb 2017 21:22:41 +0000 (+0000)
Subject: net: Avoid ABI change for min_header_len
X-Git-Tag: archive/raspbian/4.9.13-1+rpi1~11^2~23
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=c3275ccf95c761344dd180e1178584de7be07d53;p=linux-4.9.git

net: Avoid ABI change for min_header_len

Adding net_device::min_header_len is a massive ABI break that we don't
want right now.  Instead, check for the specific device types and
minimum length in dev_validate_header().


Gbp-Pq: Topic debian
Gbp-Pq: Name net-avoid-abi-change-for-min_header_len.patch
---

diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 1b65f0f975cf..6255973e3dda 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -164,7 +164,6 @@ static void loopback_setup(struct net_device *dev)
 {
 	dev->mtu		= 64 * 1024;
 	dev->hard_header_len	= ETH_HLEN;	/* 14	*/
-	dev->min_header_len	= ETH_HLEN;	/* 14	*/
 	dev->addr_len		= ETH_ALEN;	/* 6	*/
 	dev->type		= ARPHRD_LOOPBACK;	/* 0x0001*/
 	dev->flags		= IFF_LOOPBACK;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index bb9b102c15cd..6c62cd171935 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1508,7 +1508,6 @@ enum netdev_priv_flags {
  *	@mtu:		Interface MTU value
  *	@type:		Interface hardware type
  *	@hard_header_len: Maximum hardware header length.
- *	@min_header_len:  Minimum hardware header length
  *
  *	@needed_headroom: Extra headroom the hardware may need, but not in all
  *			  cases can this be guaranteed
@@ -1729,7 +1728,6 @@ struct net_device {
 	unsigned int		mtu;
 	unsigned short		type;
 	unsigned short		hard_header_len;
-	unsigned short		min_header_len;
 
 	unsigned short		needed_headroom;
 	unsigned short		needed_tailroom;
@@ -2785,7 +2783,11 @@ static inline bool dev_validate_header(const struct net_device *dev,
 {
 	if (likely(len >= dev->hard_header_len))
 		return true;
-	if (len < dev->min_header_len)
+	if ((dev->type == 1 /*ARPHRD_ETHER*/ ||
+	     dev->type == 772 /*ARPHRD_LOOPBACK*/ ||
+	     dev->type == 801 /*ARPHRD_IEEE80211*/ ||
+	     dev->type == 803 /*ARPHRD_IEEE80211_RADIOTAP*/) &&
+	    len < 14 /*ETH_HLEN*/)
 		return false;
 
 	if (capable(CAP_SYS_RAWIO)) {
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 24d7aff8db1a..02acfff36028 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -356,7 +356,6 @@ void ether_setup(struct net_device *dev)
 	dev->header_ops		= &eth_header_ops;
 	dev->type		= ARPHRD_ETHER;
 	dev->hard_header_len 	= ETH_HLEN;
-	dev->min_header_len	= ETH_HLEN;
 	dev->mtu		= ETH_DATA_LEN;
 	dev->addr_len		= ETH_ALEN;
 	dev->tx_queue_len	= 1000;	/* Ethernet wants good queues */