[source] kernel: use skb_cow_head() to deal with cloned skbs
LEDE Commits
lede-commits at lists.infradead.org
Sun Apr 23 04:51:13 PDT 2017
noltari pushed a commit to source.git, branch master:
https://git.lede-project.org/2db05cd199999d9a3670e5287d067bdab0431f1a
commit 2db05cd199999d9a3670e5287d067bdab0431f1a
Author: Álvaro Fernández Rojas <noltari at gmail.com>
AuthorDate: Sun Apr 23 13:48:05 2017 +0200
kernel: use skb_cow_head() to deal with cloned skbs
We need to ensure there is enough headroom to push extra header,
but we also need to check if we are allowed to change headers.
skb_cow_head() is the proper helper to deal with this.
Fixes Ethernet<->WiFi bridge for Raspberry Pi and probably other devices.
Signed-off-by: Álvaro Fernández Rojas <noltari at gmail.com>
---
...Use-skb_cow_head-to-deal-with-cloned-skbs.patch | 40 ++++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 36 ++++++++++++++++++
...-use-skb_cow_head-to-deal-with-cloned-skb.patch | 35 ++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 37 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 38 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 38 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 43 ++++++++++++++++++++++
...Use-skb_cow_head-to-deal-with-cloned-skbs.patch | 40 ++++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 36 ++++++++++++++++++
...-use-skb_cow_head-to-deal-with-cloned-skb.patch | 35 ++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 37 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 38 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 38 +++++++++++++++++++
...use-skb_cow_head-to-deal-with-cloned-skbs.patch | 43 ++++++++++++++++++++++
14 files changed, 534 insertions(+)
diff --git a/target/linux/generic/patches-4.4/030-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..36fb936
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,40 @@
+From e9156cd26a495a18706e796f02a81fee41ec14f4 Mon Sep 17 00:00:00 2001
+From: James Hughes <james.hughes at raspberrypi.org>
+Date: Wed, 19 Apr 2017 11:13:40 +0100
+Subject: [PATCH] smsc95xx: Use skb_cow_head to deal with cloned skbs
+
+The driver was failing to check that the SKB wasn't cloned
+before adding checksum data.
+Replace existing handling to extend/copy the header buffer
+with skb_cow_head.
+
+Signed-off-by: James Hughes <james.hughes at raspberrypi.org>
+Acked-by: Eric Dumazet <edumazet at google.com>
+Acked-by: Woojung Huh <Woojung.Huh at microchip.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/smsc95xx.c | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+--- a/drivers/net/usb/smsc95xx.c
++++ b/drivers/net/usb/smsc95xx.c
+@@ -1835,13 +1835,13 @@ static struct sk_buff *smsc95xx_tx_fixup
+ /* We do not advertise SG, so skbs should be already linearized */
+ BUG_ON(skb_shinfo(skb)->nr_frags);
+
+- if (skb_headroom(skb) < overhead) {
+- struct sk_buff *skb2 = skb_copy_expand(skb,
+- overhead, 0, flags);
++ /* Make writable and expand header space by overhead if required */
++ if (skb_cow_head(skb, overhead)) {
++ /* Must deallocate here as returning NULL to indicate error
++ * means the skb won't be deallocated in the caller.
++ */
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ if (csum) {
diff --git a/target/linux/generic/patches-4.4/030-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..6312f0f
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,36 @@
+From b7c6d2675899cfff0180412c63fc9cbd5bacdb4d Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:21 -0700
+Subject: [PATCH] smsc75xx: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: d0cad871703b ("smsc75xx: SMSC LAN75xx USB gigabit ethernet adapter driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/smsc75xx.c | 8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+--- a/drivers/net/usb/smsc75xx.c
++++ b/drivers/net/usb/smsc75xx.c
+@@ -2193,13 +2193,9 @@ static struct sk_buff *smsc75xx_tx_fixup
+ {
+ u32 tx_cmd_a, tx_cmd_b;
+
+- if (skb_headroom(skb) < SMSC75XX_TX_OVERHEAD) {
+- struct sk_buff *skb2 =
+- skb_copy_expand(skb, SMSC75XX_TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, SMSC75XX_TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ tx_cmd_a = (u32)(skb->len & TX_CMD_A_LEN) | TX_CMD_A_FCS;
diff --git a/target/linux/generic/patches-4.4/030-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch b/target/linux/generic/patches-4.4/030-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch
new file mode 100644
index 0000000..aee8aa9
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch
@@ -0,0 +1,35 @@
+From a9e840a2081ed28c2b7caa6a9a0041c950b3c37d Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:22 -0700
+Subject: [PATCH] cx82310_eth: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: cc28a20e77b2 ("introduce cx82310_eth: Conexant CX82310-based ADSL router USB ethernet driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/cx82310_eth.c | 7 ++-----
+ 1 file changed, 2 insertions(+), 5 deletions(-)
+
+--- a/drivers/net/usb/cx82310_eth.c
++++ b/drivers/net/usb/cx82310_eth.c
+@@ -293,12 +293,9 @@ static struct sk_buff *cx82310_tx_fixup(
+ {
+ int len = skb->len;
+
+- if (skb_headroom(skb) < 2) {
+- struct sk_buff *skb2 = skb_copy_expand(skb, 2, 0, flags);
++ if (skb_cow_head(skb, 2)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+ skb_push(skb, 2);
+
diff --git a/target/linux/generic/patches-4.4/030-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..4d0fcf6
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,37 @@
+From d532c1082f68176363ed766d09bf187616e282fe Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:23 -0700
+Subject: [PATCH] sr9700: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/sr9700.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/sr9700.c
++++ b/drivers/net/usb/sr9700.c
+@@ -456,14 +456,9 @@ static struct sk_buff *sr9700_tx_fixup(s
+
+ len = skb->len;
+
+- if (skb_headroom(skb) < SR_TX_OVERHEAD) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, SR_TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, SR_TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ __skb_push(skb, SR_TX_OVERHEAD);
diff --git a/target/linux/generic/patches-4.4/030-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..4f96041
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,38 @@
+From d4ca73591916b760478d2b04334d5dcadc028e9c Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:24 -0700
+Subject: [PATCH] lan78xx: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Cc: Woojung Huh <woojung.huh at microchip.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/lan78xx.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/lan78xx.c
++++ b/drivers/net/usb/lan78xx.c
+@@ -2050,14 +2050,9 @@ static struct sk_buff *lan78xx_tx_prep(s
+ {
+ u32 tx_cmd_a, tx_cmd_b;
+
+- if (skb_headroom(skb) < TX_OVERHEAD) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ if (lan78xx_linearize(skb) < 0)
diff --git a/target/linux/generic/patches-4.4/030-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..2e8bba5
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,38 @@
+From 6bc6895bdd6744e0136eaa4a11fbdb20a7db4e40 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:25 -0700
+Subject: [PATCH] ch9200: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Cc: Matthew Garrett <mjg59 at srcf.ucam.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/ch9200.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/ch9200.c
++++ b/drivers/net/usb/ch9200.c
+@@ -255,14 +255,9 @@ static struct sk_buff *ch9200_tx_fixup(s
+ tx_overhead = 0x40;
+
+ len = skb->len;
+- if (skb_headroom(skb) < tx_overhead) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, tx_overhead, 0, flags);
++ if (skb_cow_head(skb, tx_overhead)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ __skb_push(skb, tx_overhead);
diff --git a/target/linux/generic/patches-4.4/030-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.4/030-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..541c694
--- /dev/null
+++ b/target/linux/generic/patches-4.4/030-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,43 @@
+From 39fba7835aacda65284a86e611774cbba71dac20 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:26 -0700
+Subject: [PATCH] kaweth: use skb_cow_head() to deal with cloned skbs
+
+We can use skb_cow_head() to properly deal with clones,
+especially the ones coming from TCP stack that allow their head being
+modified. This avoids a copy.
+
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/kaweth.c | 18 ++++++------------
+ 1 file changed, 6 insertions(+), 12 deletions(-)
+
+--- a/drivers/net/usb/kaweth.c
++++ b/drivers/net/usb/kaweth.c
+@@ -812,18 +812,12 @@ static netdev_tx_t kaweth_start_xmit(str
+ }
+
+ /* We now decide whether we can put our special header into the sk_buff */
+- if (skb_cloned(skb) || skb_headroom(skb) < 2) {
+- /* no such luck - we make our own */
+- struct sk_buff *copied_skb;
+- copied_skb = skb_copy_expand(skb, 2, 0, GFP_ATOMIC);
+- dev_kfree_skb_irq(skb);
+- skb = copied_skb;
+- if (!copied_skb) {
+- kaweth->stats.tx_errors++;
+- netif_start_queue(net);
+- spin_unlock_irq(&kaweth->device_lock);
+- return NETDEV_TX_OK;
+- }
++ if (skb_cow_head(skb, 2)) {
++ kaweth->stats.tx_errors++;
++ netif_start_queue(net);
++ spin_unlock_irq(&kaweth->device_lock);
++ dev_kfree_skb_any(skb);
++ return NETDEV_TX_OK;
+ }
+
+ private_header = (__le16 *)__skb_push(skb, 2);
diff --git a/target/linux/generic/patches-4.9/023-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..cfc9abb
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-1-smsc95xx-Use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,40 @@
+From e9156cd26a495a18706e796f02a81fee41ec14f4 Mon Sep 17 00:00:00 2001
+From: James Hughes <james.hughes at raspberrypi.org>
+Date: Wed, 19 Apr 2017 11:13:40 +0100
+Subject: [PATCH] smsc95xx: Use skb_cow_head to deal with cloned skbs
+
+The driver was failing to check that the SKB wasn't cloned
+before adding checksum data.
+Replace existing handling to extend/copy the header buffer
+with skb_cow_head.
+
+Signed-off-by: James Hughes <james.hughes at raspberrypi.org>
+Acked-by: Eric Dumazet <edumazet at google.com>
+Acked-by: Woojung Huh <Woojung.Huh at microchip.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/smsc95xx.c | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+--- a/drivers/net/usb/smsc95xx.c
++++ b/drivers/net/usb/smsc95xx.c
+@@ -2001,13 +2001,13 @@ static struct sk_buff *smsc95xx_tx_fixup
+ /* We do not advertise SG, so skbs should be already linearized */
+ BUG_ON(skb_shinfo(skb)->nr_frags);
+
+- if (skb_headroom(skb) < overhead) {
+- struct sk_buff *skb2 = skb_copy_expand(skb,
+- overhead, 0, flags);
++ /* Make writable and expand header space by overhead if required */
++ if (skb_cow_head(skb, overhead)) {
++ /* Must deallocate here as returning NULL to indicate error
++ * means the skb won't be deallocated in the caller.
++ */
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ if (csum) {
diff --git a/target/linux/generic/patches-4.9/023-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..99d98e1
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-2-smsc75xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,36 @@
+From b7c6d2675899cfff0180412c63fc9cbd5bacdb4d Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:21 -0700
+Subject: [PATCH] smsc75xx: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: d0cad871703b ("smsc75xx: SMSC LAN75xx USB gigabit ethernet adapter driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/smsc75xx.c | 8 ++------
+ 1 file changed, 2 insertions(+), 6 deletions(-)
+
+--- a/drivers/net/usb/smsc75xx.c
++++ b/drivers/net/usb/smsc75xx.c
+@@ -2205,13 +2205,9 @@ static struct sk_buff *smsc75xx_tx_fixup
+ {
+ u32 tx_cmd_a, tx_cmd_b;
+
+- if (skb_headroom(skb) < SMSC75XX_TX_OVERHEAD) {
+- struct sk_buff *skb2 =
+- skb_copy_expand(skb, SMSC75XX_TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, SMSC75XX_TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ tx_cmd_a = (u32)(skb->len & TX_CMD_A_LEN) | TX_CMD_A_FCS;
diff --git a/target/linux/generic/patches-4.9/023-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch b/target/linux/generic/patches-4.9/023-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch
new file mode 100644
index 0000000..aee8aa9
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-3-cx82310_eth-use-skb_cow_head-to-deal-with-cloned-skb.patch
@@ -0,0 +1,35 @@
+From a9e840a2081ed28c2b7caa6a9a0041c950b3c37d Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:22 -0700
+Subject: [PATCH] cx82310_eth: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: cc28a20e77b2 ("introduce cx82310_eth: Conexant CX82310-based ADSL router USB ethernet driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/cx82310_eth.c | 7 ++-----
+ 1 file changed, 2 insertions(+), 5 deletions(-)
+
+--- a/drivers/net/usb/cx82310_eth.c
++++ b/drivers/net/usb/cx82310_eth.c
+@@ -293,12 +293,9 @@ static struct sk_buff *cx82310_tx_fixup(
+ {
+ int len = skb->len;
+
+- if (skb_headroom(skb) < 2) {
+- struct sk_buff *skb2 = skb_copy_expand(skb, 2, 0, flags);
++ if (skb_cow_head(skb, 2)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+ skb_push(skb, 2);
+
diff --git a/target/linux/generic/patches-4.9/023-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..4d0fcf6
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-4-sr9700-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,37 @@
+From d532c1082f68176363ed766d09bf187616e282fe Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:23 -0700
+Subject: [PATCH] sr9700: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: c9b37458e956 ("USB2NET : SR9700 : One chip USB 1.1 USB2NET SR9700Device Driver Support")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/sr9700.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/sr9700.c
++++ b/drivers/net/usb/sr9700.c
+@@ -456,14 +456,9 @@ static struct sk_buff *sr9700_tx_fixup(s
+
+ len = skb->len;
+
+- if (skb_headroom(skb) < SR_TX_OVERHEAD) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, SR_TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, SR_TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ __skb_push(skb, SR_TX_OVERHEAD);
diff --git a/target/linux/generic/patches-4.9/023-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..ea82799
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-5-lan78xx-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,38 @@
+From d4ca73591916b760478d2b04334d5dcadc028e9c Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:24 -0700
+Subject: [PATCH] lan78xx: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: 55d7de9de6c3 ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Cc: Woojung Huh <woojung.huh at microchip.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/lan78xx.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/lan78xx.c
++++ b/drivers/net/usb/lan78xx.c
+@@ -2419,14 +2419,9 @@ static struct sk_buff *lan78xx_tx_prep(s
+ {
+ u32 tx_cmd_a, tx_cmd_b;
+
+- if (skb_headroom(skb) < TX_OVERHEAD) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, TX_OVERHEAD, 0, flags);
++ if (skb_cow_head(skb, TX_OVERHEAD)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ if (lan78xx_linearize(skb) < 0)
diff --git a/target/linux/generic/patches-4.9/023-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..83de38b
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-6-ch9200-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,38 @@
+From 6bc6895bdd6744e0136eaa4a11fbdb20a7db4e40 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:25 -0700
+Subject: [PATCH] ch9200: use skb_cow_head() to deal with cloned skbs
+
+We need to ensure there is enough headroom to push extra header,
+but we also need to check if we are allowed to change headers.
+
+skb_cow_head() is the proper helper to deal with this.
+
+Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Cc: Matthew Garrett <mjg59 at srcf.ucam.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/ch9200.c | 9 ++-------
+ 1 file changed, 2 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/usb/ch9200.c
++++ b/drivers/net/usb/ch9200.c
+@@ -254,14 +254,9 @@ static struct sk_buff *ch9200_tx_fixup(s
+ tx_overhead = 0x40;
+
+ len = skb->len;
+- if (skb_headroom(skb) < tx_overhead) {
+- struct sk_buff *skb2;
+-
+- skb2 = skb_copy_expand(skb, tx_overhead, 0, flags);
++ if (skb_cow_head(skb, tx_overhead)) {
+ dev_kfree_skb_any(skb);
+- skb = skb2;
+- if (!skb)
+- return NULL;
++ return NULL;
+ }
+
+ __skb_push(skb, tx_overhead);
diff --git a/target/linux/generic/patches-4.9/023-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch b/target/linux/generic/patches-4.9/023-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch
new file mode 100644
index 0000000..597f25b
--- /dev/null
+++ b/target/linux/generic/patches-4.9/023-7-kaweth-use-skb_cow_head-to-deal-with-cloned-skbs.patch
@@ -0,0 +1,43 @@
+From 39fba7835aacda65284a86e611774cbba71dac20 Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet at google.com>
+Date: Wed, 19 Apr 2017 09:59:26 -0700
+Subject: [PATCH] kaweth: use skb_cow_head() to deal with cloned skbs
+
+We can use skb_cow_head() to properly deal with clones,
+especially the ones coming from TCP stack that allow their head being
+modified. This avoids a copy.
+
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Cc: James Hughes <james.hughes at raspberrypi.org>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ drivers/net/usb/kaweth.c | 18 ++++++------------
+ 1 file changed, 6 insertions(+), 12 deletions(-)
+
+--- a/drivers/net/usb/kaweth.c
++++ b/drivers/net/usb/kaweth.c
+@@ -803,18 +803,12 @@ static netdev_tx_t kaweth_start_xmit(str
+ }
+
+ /* We now decide whether we can put our special header into the sk_buff */
+- if (skb_cloned(skb) || skb_headroom(skb) < 2) {
+- /* no such luck - we make our own */
+- struct sk_buff *copied_skb;
+- copied_skb = skb_copy_expand(skb, 2, 0, GFP_ATOMIC);
+- dev_kfree_skb_irq(skb);
+- skb = copied_skb;
+- if (!copied_skb) {
+- kaweth->stats.tx_errors++;
+- netif_start_queue(net);
+- spin_unlock_irq(&kaweth->device_lock);
+- return NETDEV_TX_OK;
+- }
++ if (skb_cow_head(skb, 2)) {
++ kaweth->stats.tx_errors++;
++ netif_start_queue(net);
++ spin_unlock_irq(&kaweth->device_lock);
++ dev_kfree_skb_any(skb);
++ return NETDEV_TX_OK;
+ }
+
+ private_header = (__le16 *)__skb_push(skb, 2);
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