Gertjan van Wingerde a écrit :
On 12/01/09 00:46, Benoit PAPILLAULT wrote:
Gertjan van Wingerde a écrit :
The L2 padding fixes patch has grown a bit and now consists of 4 separate
patches to clean the L2 padding code up and to fix a number of bugs at the
same time.
1. rt2x00: Further L2 padding fixes.
2. rt2x00: Remove SKBDESC_L2_PADDED flag.
3. rt2x00: Reorganize L2 padding inserting function.
4. rt2x00: Only remove L2 padding in received frames if there is payload.
---
Gertjan.
Thanks Gertjan for the patches, I know that padding is a bit of
nightware. I've testing your tree and here are the results:
1. On TX : It fails for control frames with hdrlen=10 since it will
produce l2pad = 2 in your case, where it should be 0. In all other
cases, it works!
Hmm. That's strange, as patch 3 of the series should have handled this. Basically this patch
checks if a frame actually has payload, and refrains from inserting l2pad and payload alignment
in that case.
How did you detect this failure?
I sent every possible frame type in monitor and compared with what ath9k
in monitor mode received.
What did you observe on the "wire", i.e. how was the frame malformed because of this?
For instance, i sent :
c400c400c40000000000 (10 bytes)
and I received :
c400ca00c400000000000000 (12 bytes)
You can see the 2 bytes added at the end (bytes 2-3 are modified by the
HW since it contains the duration_id)
Also, would it be possible to get some of the skb details of a frame that fails?
I'll redo the test. What details do you want?
Solution : padding is only needed for data frames for rt28x devices, so
I think it's better to something like rt2xqueue_padpos
[http://git.popipo.fr/?p=rt2x00.git;a=commitdiff;h=95ddf076c13062d1026025d97ba511f880a1792d]
I'm still not fond of using detailed ieee 802.11 frame format knowledge to do this. I prefer
to use standard mac80211 functions with a bit of detection on the actual skb.
If you want to use mac80211 functions, we can do something like that :
/*
* Determine the L2 padding size based on the 802.11 header length
*
* Exact formula is (4 - (header_length%4))%4 but since header_length is
* always a multiple of 2, we could simplify to (header_length&3).
*
* L2PAD is only present for data frame and an easy way to check for that is
* to compare header_length with 24 bytes.
*/
#define L2PAD_SIZE(__header) \
((__header)<24 ? 0 : ((4 - ((__header)%4))%4))
Regards,
Benoit
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
