[PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[Venkat Duvvuru]

ethtool_rxfh_indir_default is invoked inside ethtool_set_rxfh_indir when
user_size is zero. However user_size can only be zero when dev_size is
zero in which case ethtool_get_rxfh_indir itself would return
EOPNOTSUPP error. "user_size = 0" can never happen unless userspace
ethtool sends user_size as zero beforing invoking the ioctl for
ETHTOOL_SRSSH, in which case we should return -EINVAL.

v2: Modified commit message.

Signed-off-by: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>
---
 net/core/ethtool.c |   33 ++++++++++++++-------------------
 1 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 30071de..9d96516 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -626,7 +626,7 @@ static noinline_for_stack int ethtool_set_rxfh_indir(struct net_device *dev,
 			   sizeof(user_size)))
 		return -EFAULT;
 
-	if (user_size != 0 && user_size != dev_size)
+	if (!user_size || user_size != dev_size)
 		return -EINVAL;
 
 	indir = kcalloc(dev_size, sizeof(indir[0]), GFP_USER);
@@ -638,25 +638,20 @@ static noinline_for_stack int ethtool_set_rxfh_indir(struct net_device *dev,
 	if (ret)
 		goto out;
 
-	if (user_size == 0) {
-		for (i = 0; i < dev_size; i++)
-			indir[i] = ethtool_rxfh_indir_default(i, rx_rings.data);
-	} else {
-		if (copy_from_user(indir,
-				  useraddr +
-				  offsetof(struct ethtool_rxfh_indir,
-					   ring_index[0]),
-				  dev_size * sizeof(indir[0]))) {
-			ret = -EFAULT;
-			goto out;
-		}
+	if (copy_from_user(indir,
+			   useraddr +
+			   offsetof(struct ethtool_rxfh_indir,
+				    ring_index[0]),
+			   dev_size * sizeof(indir[0]))) {
+		ret = -EFAULT;
+		goto out;
+	}
 
-		/* Validate ring indices */
-		for (i = 0; i < dev_size; i++) {
-			if (indir[i] >= rx_rings.data) {
-				ret = -EINVAL;
-				goto out;
-			}
+	/* Validate ring indices */
+	for (i = 0; i < dev_size; i++) {
+		if (indir[i] >= rx_rings.data) {
+			ret = -EINVAL;
+			goto out;
 		}
 	}
 
-- 
1.7.1

Re: [PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[David Miller]

From: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>
Date: Wed, 19 Feb 2014 13:20:25 +0530

> ethtool_rxfh_indir_default is invoked inside ethtool_set_rxfh_indir when
> user_size is zero. However user_size can only be zero when dev_size is
> zero in which case ethtool_get_rxfh_indir itself would return
> EOPNOTSUPP error. "user_size = 0" can never happen unless userspace
> ethtool sends user_size as zero beforing invoking the ioctl for
> ETHTOOL_SRSSH, in which case we should return -EINVAL.
> 
> v2: Modified commit message.
> 
> Signed-off-by: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>

It looks like the author of this code intended user_size == 0 as a way
to reset the indirection table to the default, did this ever work?

RE: [PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[Venkata Duvvuru]

> From: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>
> Date: Wed, 19 Feb 2014 13:20:25 +0530
> 
> > ethtool_rxfh_indir_default is invoked inside ethtool_set_rxfh_indir
> > when user_size is zero. However user_size can only be zero when
> > dev_size is zero in which case ethtool_get_rxfh_indir itself would
> > return EOPNOTSUPP error. "user_size = 0" can never happen unless
> > userspace ethtool sends user_size as zero beforing invoking the ioctl
> > for ETHTOOL_SRSSH, in which case we should return -EINVAL.
> >
> > v2: Modified commit message.
> >
> > Signed-off-by: Venkat Duvvuru <VenkatKumar.Duvvuru@Emulex.com>
> 
> It looks like the author of this code intended user_size == 0 as a way to reset
> the indirection table to the default, did this ever work?

There is no option for --set-rxfh-indir to reset the indirection table. So ethtool cannot know that it has to fill user_size = 0 to reset the indirection table to default.

Re: [PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[David Miller]

From: Venkata Duvvuru <VenkatKumar.Duvvuru@Emulex.Com>
Date: Fri, 21 Feb 2014 10:28:24 +0000

> There is no option for --set-rxfh-indir to reset the indirection table.

But this can be easily added to ethtool.

My point is that the intention is _clearly_ there to provide this
facility.

Re: [PATCH v2 net-next] ethtool: Remove inactive code snippet in ethtool_set_rxfh_indir

[Ben Hutchings]

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On Fri, 2014-02-21 at 12:14 -0500, David Miller wrote:
> From: Venkata Duvvuru <VenkatKumar.Duvvuru@Emulex.Com>
> Date: Fri, 21 Feb 2014 10:28:24 +0000
> 
> > There is no option for --set-rxfh-indir to reset the indirection table.
> 
> But this can be easily added to ethtool.
> 
> My point is that the intention is _clearly_ there to provide this
> facility.

This is indeed intentional, and was added by:

commit 278bc4296bd64ffd1d3913b487dc8a520e423a7a
Author: Ben Hutchings <bhutchings@solarflare.com>
Date:   Thu Dec 15 13:56:49 2011 +0000

    ethtool: Define and apply a default policy for RX flow hash indirection

I can't remember whether I wrote a patch for ethtool to use this feature
but I must have tested it somehow...  The ethtool command isn't the only
user of the ethtool API, in any case.

Ben.

-- 
Ben Hutchings
A free society is one where it is safe to be unpopular. - Adlai Stevenson

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