Re: [ethtool PATCH 4/4] v5 Add RX packet classification interface

On 05/04/2011 10:24 AM, Ben Hutchings wrote:

On Wed, 2011-05-04 at 10:09 -0700, Dimitris Michailidis wrote:

quoted

On 05/03/2011 04:34 PM, Ben Hutchings wrote:

quoted

On Tue, 2011-05-03 at 16:23 -0700, Dimitris Michailidis wrote:

quoted

I think RX_CLS_LOC_UNSPEC should be passed to the driver, where there is 
enough knowledge to pick an appropriate slot.  So I'd remove the

     if (loc == RX_CLS_LOC_UNSPEC)

block above, let the driver pick a slot, and then pass the selected location 
back for ethtool to report.

But first we have to specify this in the ethtool API.  So please propose
a patch to ethtool.h.

In the past we discussed that being able to specify the first available slot or 
the last available would be useful, so something like the below?

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 4194a20..909ef79 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h

@@ -442,7 +442,8 @@ struct ethtool_flow_ext {
   *	includes the %FLOW_EXT flag.
   * @ring_cookie: RX ring/queue index to deliver to, or %RX_CLS_FLOW_DISC
   *	if packets should be discarded
- * @location: Index of filter in hardware table
+ * @location: Index of filter in hardware table, or %RX_CLS_FLOW_FIRST_LOC for
+ *	first available index, or %RX_CLS_FLOW_LAST_LOC for last available

[...]

I think that's reasonable.  We should also explicitly state that
location determines priority, i.e. if a packet matches two filters then
the one with the lower location wins.

Easy and true for a TCAM.  For hashing would you use the location to decide how 
to order filters that fall in the same bucket?