LARTC - Apr 2007 - Problem setting shift value in tcindex filter on big endian machine

Hi all,

I''m trying to get some DiffServ QoS shaping to work on an XScale 
machine, running big endian. I''m setting it up with tc. Using the 
tcindex filter I found that regardless what shift value I enter, only 
''0'' is returned when I list the filters afterwards. The very
same rules
work fine on my (little endian) PC.
Looking at the code (iproute2-2.6.18-061002) I found that tc (in 
tc/f_tcindex.c, line 72 and after) sends the shift value to the kernel 
as an int. The kernel, however, expects it as a ''u16'' 
(net/sched/cls_tcindex.c, around line 250 depending on the exact kernel 
version). I checked 2.6 kernel versions back until 2.6.11.

So... do we have a type mismatch here? As ''shift'' is the last
parameter
in the buffer, this works still very well on a little endian machine, 
however on a big endian machine allways 0 is received in the kernel. To 
check that I changed the type of the shift value to unsigned short in 
tc, and that fixed it for me.
Someone interested in a patch?


Regards
Ole

Please send bugreports to netdev@vger.kernel.org.

Ole Reinartz wrote:
> I''m trying to get some DiffServ QoS shaping to work on an XScale
> machine, running big endian. I''m setting it up with tc. Using the
> tcindex filter I found that regardless what shift value I enter, only
> ''0'' is returned when I list the filters afterwards. The
very same rules
> work fine on my (little endian) PC.
> Looking at the code (iproute2-2.6.18-061002) I found that tc (in
> tc/f_tcindex.c, line 72 and after) sends the shift value to the kernel
> as an int. The kernel, however, expects it as a ''u16''
> (net/sched/cls_tcindex.c, around line 250 depending on the exact kernel
> version). I checked 2.6 kernel versions back until 2.6.11.

It appears this was broken during some ->change operation fixes
in 2.6.11.
> So... do we have a type mismatch here? As ''shift'' is the
last parameter
> in the buffer, this works still very well on a little endian machine,
> however on a big endian machine allways 0 is received in the kernel. To
> check that I changed the type of the shift value to unsigned short in
> tc, and that fixed it for me.
> Someone interested in a patch?

Yes, but its the kernel that needs to be fixed to expect a u32.

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