Patchwork [3.5.y.z,extended,stable] Patch "usbnet: do not pretend to support SG/TSO" has been added to staging queue

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Submitter Luis Henriques
Date Aug. 6, 2013, 9:36 a.m.
Message ID <1375781808-8109-1-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/264946/
State New
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Comments

Luis Henriques - Aug. 6, 2013, 9:36 a.m.
This is a note to let you know that I have just added a patch titled

    usbnet: do not pretend to support SG/TSO

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From 64535158530a19dbd51140001a3d78cb1f1c7a74 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 23 Jul 2013 17:15:54 -0700
Subject: [PATCH] usbnet: do not pretend to support SG/TSO

commit 20f0170377264e8449b6987041f0bcc4d746d3ed upstream.

usbnet doesn't support yet SG, so drivers should not advertise SG or TSO
capabilities, as they allow TCP stack to build large TSO packets that
need to be linearized and might use order-5 pages.

This adds an extra copy overhead and possible allocation failures.

Current code ignore skb_linearize() return code so crashes are even
possible.

Best is to not pretend SG/TSO is supported, and add this again when/if
usbnet really supports SG for devices who could get a performance gain.

Based on a prior patch from Freddy Xin <freddy@asix.com.tw>

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[ luis: backported to 3.5:
  - adjusted context
  - dropped changes to ASIX AX88179/178A driver ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/net/usb/smsc75xx.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

--
1.8.3.2

Patch

diff --git a/drivers/net/usb/smsc75xx.c b/drivers/net/usb/smsc75xx.c
index 2e50fbb..c241ae7 100644
--- a/drivers/net/usb/smsc75xx.c
+++ b/drivers/net/usb/smsc75xx.c
@@ -43,7 +43,6 @@ 
 #define EEPROM_MAC_OFFSET		(0x01)
 #define DEFAULT_TX_CSUM_ENABLE		(true)
 #define DEFAULT_RX_CSUM_ENABLE		(true)
-#define DEFAULT_TSO_ENABLE		(true)
 #define SMSC75XX_INTERNAL_PHY_ID	(1)
 #define SMSC75XX_TX_OVERHEAD		(8)
 #define MAX_RX_FIFO_SIZE		(20 * 1024)
@@ -1053,17 +1052,14 @@  static int smsc75xx_bind(struct usbnet *dev, struct usb_interface *intf)

 	INIT_WORK(&pdata->set_multicast, smsc75xx_deferred_multicast_write);

-	if (DEFAULT_TX_CSUM_ENABLE) {
+	if (DEFAULT_TX_CSUM_ENABLE)
 		dev->net->features |= NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM;
-		if (DEFAULT_TSO_ENABLE)
-			dev->net->features |= NETIF_F_SG |
-				NETIF_F_TSO | NETIF_F_TSO6;
-	}
+
 	if (DEFAULT_RX_CSUM_ENABLE)
 		dev->net->features |= NETIF_F_RXCSUM;

 	dev->net->hw_features = NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM |
-		NETIF_F_SG | NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_RXCSUM;
+				NETIF_F_RXCSUM;

 	/* Init all registers */
 	ret = smsc75xx_reset(dev);
@@ -1188,8 +1184,6 @@  static struct sk_buff *smsc75xx_tx_fixup(struct usbnet *dev,
 {
 	u32 tx_cmd_a, tx_cmd_b;

-	skb_linearize(skb);
-
 	if (skb_headroom(skb) < SMSC75XX_TX_OVERHEAD) {
 		struct sk_buff *skb2 =
 			skb_copy_expand(skb, SMSC75XX_TX_OVERHEAD, 0, flags);