[PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[Ben Hutchings]

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When the ETHTOOL_GLINKSETTINGS implementation finds that userland is
using the wrong number of words of link mode bitmaps (or is trying to
find out the right numbers) it sets the cmd field to 0 in the response
structure.

This is inconsistent with the implementation of every other ethtool
command, so let's remove that inconsistency before it gets into a
stable release.

Fixes: 3f1ac7a700d03 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS API")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
David, please can you include this in changes for 4.6?

Ben.

 net/core/ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 2966cd0d7c93..f426c5ad6149 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -655,7 +655,7 @@ static int ethtool_get_link_ksettings(struct net_device *dev,
 	    != link_ksettings.base.link_mode_masks_nwords) {
 		/* wrong link mode nbits requested */
 		memset(&link_ksettings, 0, sizeof(link_ksettings));
-		/* keep cmd field reset to 0 */
+		link_ksettings.base.cmd = ETHTOOL_GLINKSETTINGS;
 		/* send back number of words required as negative val */
 		compiletime_assert(__ETHTOOL_LINK_MODE_MASK_NU32 <= S8_MAX,
 				   "need too many bits for link modes!");

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Re: [PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[david decotigny]

Ben Hutchings <ben <at> decadent.org.uk> writes:
> 
> When the ETHTOOL_GLINKSETTINGS implementation finds that userland is
> using the wrong number of words of link mode bitmaps (or is trying to
> find out the right numbers) it sets the cmd field to 0 in the response
> structure.
> 
> This is inconsistent with the implementation of every other ethtool
> command, so let's remove that inconsistency before it gets into a
> stable release.
> 
> Fixes: 3f1ac7a700d03 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS API")
> Signed-off-by: Ben Hutchings <ben <at> decadent.org.uk>
> ---
> David, please can you include this in changes for 4.6?
> 
> Ben.
> 
>  net/core/ethtool.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index 2966cd0d7c93..f426c5ad6149 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
>  <at>  <at>  -655,7 +655,7  <at>  <at>  static int 
ethtool_get_link_ksettings(struct net_device *dev,
>  	    != link_ksettings.base.link_mode_masks_nwords) {
>  		/* wrong link mode nbits requested */
>  		memset(&link_ksettings, 0, sizeof(link_ksettings));
> -		/* keep cmd field reset to 0 */
> +		link_ksettings.base.cmd = ETHTOOL_GLINKSETTINGS;
>  		/* send back number of words required as negative val */
>  		compiletime_assert(__ETHTOOL_LINK_MODE_MASK_NU32 <= S8_MAX,
>  				   "need too many bits for link modes!");
> 

thanks!

Please also update the comments in ethtool.h, proposed change below:

diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index 2835b07..9222db8 100644
--- a/include/uapi/linux/ethtool.h
+++ b/include/uapi/linux/ethtool.h
@@ -1648,9 +1648,9 @@ enum ethtool_reset_flags {
  *	%ETHTOOL_GLINKSETTINGS: on entry, number of words passed by user
  *	(>= 0); on return, if handshake in progress, negative if
  *	request size unsupported by kernel: absolute value indicates
- *	kernel recommended size and cmd field is 0, as well as all the
- *	other fields; otherwise (handshake completed), strictly
- *	positive to indicate size used by kernel and cmd field is
+ *	kernel expected size and all the other fields but cmd
+ *	are 0; otherwise (handshake completed), strictly positive
+ *	to indicate size used by kernel and cmd field stays
  *	%ETHTOOL_GLINKSETTINGS, all other fields populated by driver. For
  *	%ETHTOOL_SLINKSETTINGS: must be valid on entry, ie. a positive
  *	value returned previously by %ETHTOOL_GLINKSETTINGS, otherwise

Re: [PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[David Miller]

From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 14 Mar 2016 01:05:38 +0000

> When the ETHTOOL_GLINKSETTINGS implementation finds that userland is
> using the wrong number of words of link mode bitmaps (or is trying to
> find out the right numbers) it sets the cmd field to 0 in the response
> structure.
> 
> This is inconsistent with the implementation of every other ethtool
> command, so let's remove that inconsistency before it gets into a
> stable release.
> 
> Fixes: 3f1ac7a700d03 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS API")
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

Applied and queued up for -stable, thanks Ben.

Re: [PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[Ben Hutchings]

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On Wed, 2016-03-16 at 19:26 -0400, David Miller wrote:
> From: Ben Hutchings <ben@decadent.org.uk>
> Date: Mon, 14 Mar 2016 01:05:38 +0000
> 
> > When the ETHTOOL_GLINKSETTINGS implementation finds that userland is
> > using the wrong number of words of link mode bitmaps (or is trying to
> > find out the right numbers) it sets the cmd field to 0 in the response
> > structure.
> > 
> > This is inconsistent with the implementation of every other ethtool
> > command, so let's remove that inconsistency before it gets into a
> > stable release.
> > 
> > Fixes: 3f1ac7a700d03 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS API")
> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
> 
> Applied and queued up for -stable, thanks Ben.

This doesn't need fixing in any stable release.

Ben.

-- 
Ben Hutchings
If you seem to know what you are doing, you'll be given more to do.

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Re: [PATCH net-next] ethtool: Set cmd field in ETHTOOL_GLINKSETTINGS response to wrong nwords

[David Miller]

From: Ben Hutchings <ben@decadent.org.uk>
Date: Wed, 16 Mar 2016 23:36:32 +0000

> On Wed, 2016-03-16 at 19:26 -0400, David Miller wrote:
>> From: Ben Hutchings <ben@decadent.org.uk>
>> Date: Mon, 14 Mar 2016 01:05:38 +0000
>> 
>> > When the ETHTOOL_GLINKSETTINGS implementation finds that userland is
>> > using the wrong number of words of link mode bitmaps (or is trying to
>> > find out the right numbers) it sets the cmd field to 0 in the response
>> > structure.
>> > 
>> > This is inconsistent with the implementation of every other ethtool
>> > command, so let's remove that inconsistency before it gets into a
>> > stable release.
>> > 
>> > Fixes: 3f1ac7a700d03 ("net: ethtool: add new ETHTOOL_xLINKSETTINGS API")
>> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
>> 
>> Applied and queued up for -stable, thanks Ben.
> 
> This doesn't need fixing in any stable release.

My bad I thought it was needed for 4.5-final.