[PATCH] e1000e: disable rxhash when try to enable jumbo frame also rxhash and rxcsum have enabled

[PATCH] e1000e: disable rxhash when try to enable jumbo frame also rxhash and rxcsum have enabled

[Joe Jin]

Upstream commit 70495a5 check if both rxhash and rxcsum enabled when enabling
jumbo frames and disallowed all of them enabled at the same time.

Since jumbo frame widely be used in real world, so when try to enable jumbo
frames but rxhash and rxcsum have enabled, change the default behavior to
disable receive hashing.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Guru Anbalagane <guru.anbalagane@oracle.com>
Acked-by: Adnan Misherfi <adnan.misherfi@oracle.com>
Cc: David S. Miller <davem@davemloft.net>
---
 drivers/net/ethernet/intel/e1000e/netdev.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index a4b0435..b9f0857 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -66,6 +66,8 @@ module_param(debug, int, 0);
 MODULE_PARM_DESC(debug, "Debug level (0=none,...,16=all)");
 
 static void e1000e_disable_aspm(struct pci_dev *pdev, u16 state);
+static int e1000_set_features(struct net_device *netdev,
+			      netdev_features_t features);
 
 static const struct e1000_info *e1000_info_tbl[] = {
 	[board_82571]		= &e1000_82571_info,
@@ -5254,8 +5256,15 @@ static int e1000_change_mtu(struct net_device *netdev, int new_mtu)
 		 */
 		if ((netdev->features & NETIF_F_RXCSUM) &&
 		    (netdev->features & NETIF_F_RXHASH)) {
-			e_err("Jumbo frames cannot be enabled when both receive checksum offload and receive hashing are enabled.  Disable one of the receive offload features before enabling jumbos.\n");
-			return -EINVAL;
+			netdev_features_t features;
+
+			/* Disable receive hashing if conflicted */
+			features = netdev->features & (~NETIF_F_RXHASH);
+			if (e1000_set_features(netdev, features)) {
+				e_err("Jumbo frames cannot be enabled when both receive checksum offload and receive hashing are enabled.  Disable one of the receive offload features before enabling jumbos.\n");
+				return -EINVAL;
+			}
+			e_info("Jumbo frames cannot be enabled when both receive checksum offload and receive hashing are enabled. Disabling Receive Hashing.\n");
 		}
 	}
 
-- 
1.7.10.2


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Re: [PATCH] e1000e: disable rxhash when try to enable jumbo frame also rxhash and rxcsum have enabled

[David Miller]

From: Joe Jin <joe.jin@oracle.com>
Date: Fri, 08 Jun 2012 09:06:40 +0800

> Upstream commit 70495a5 check if both rxhash and rxcsum enabled when enabling
> jumbo frames and disallowed all of them enabled at the same time.
> 
> Since jumbo frame widely be used in real world, so when try to enable jumbo
> frames but rxhash and rxcsum have enabled, change the default behavior to
> disable receive hashing.
> 
> Signed-off-by: Joe Jin <joe.jin@oracle.com>
> Signed-off-by: Guru Anbalagane <guru.anbalagane@oracle.com>
> Acked-by: Adnan Misherfi <adnan.misherfi@oracle.com>

If I were the Intel developers I would not apply this patch, it sets
a very bad precedence.

The tool tells you that the combination you're attempting to use is
invalid, and the kernel log message tells you exactly why.

The driver should never automatically change configuration settings
not actually requested by the user.

Re: [PATCH] e1000e: disable rxhash when try to enable jumbo frame also rxhash and rxcsum have enabled

[Allan, Bruce W]

> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Thursday, June 07, 2012 6:12 PM
> To: joe.jin@oracle.com
> Cc: e1000-devel@lists.sourceforge.net; guru.anbalagane@oracle.com;
> Allan, Bruce W; Brandeburg, Jesse; adnan.misherfi@oracle.com; Ronciak,
> John; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [E1000-devel] [PATCH] e1000e: disable rxhash when try to
> enable jumbo frame also rxhash and rxcsum have enabled
> 
> From: Joe Jin <joe.jin@oracle.com>
> Date: Fri, 08 Jun 2012 09:06:40 +0800
> 
> > Upstream commit 70495a5 check if both rxhash and rxcsum enabled when
> enabling
> > jumbo frames and disallowed all of them enabled at the same time.
> >
> > Since jumbo frame widely be used in real world, so when try to
> enable jumbo
> > frames but rxhash and rxcsum have enabled, change the default
> behavior to
> > disable receive hashing.
> >
> > Signed-off-by: Joe Jin <joe.jin@oracle.com>
> > Signed-off-by: Guru Anbalagane <guru.anbalagane@oracle.com>
> > Acked-by: Adnan Misherfi <adnan.misherfi@oracle.com>
> 
> If I were the Intel developers I would not apply this patch, it sets
> a very bad precedence.
> 
> The tool tells you that the combination you're attempting to use is
> invalid, and the kernel log message tells you exactly why.
> 
> The driver should never automatically change configuration settings
> not actually requested by the user.

I've been working on another patch that removes the issue with disabling
one feature over another altogether, so this patch would be moot.  It will
be pushed to our internal testing organization in the next day or two.


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threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
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