2014-08-13 14:01:41

by Lukasz Rymanowski

Subject: [PATCH] Bluetooth: Improve data packing in SAR mode

There is no need to decrease pdu size with L2CAP SDU lenght in Start
L2CAP SDU frame. Start packtet is just 2 bytes longer as specified and
we can keep payload as long as possible.

Signed-off-by: Lukasz Rymanowski <[email protected]>
---
When testing SAR L2CAP against PTS, L2CAP channel is usually
configured in that way, that SDU = MPS * 3. PTS expets then 3
I-Frames from IUT: Start, Continuation and End frame.

Without this fix, we sent 4 I-Frames. We could pass a test
by using -b option in l2test and send just two bytes less than
SDU length but it was hakish :) With this patch no need to use -b
option.

net/bluetooth/l2cap_core.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 7b0d744..8fe9f4b 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2276,7 +2276,6 @@ static int l2cap_segment_sdu(struct l2cap_chan *chan,
} else {
sar = L2CAP_SAR_START;
sdu_len = len;
- pdu_len -= L2CAP_SDULEN_SIZE;
}

while (len > 0) {
@@ -2291,10 +2290,8 @@ static int l2cap_segment_sdu(struct l2cap_chan *chan,
__skb_queue_tail(seg_queue, skb);

len -= pdu_len;
- if (sdu_len) {
+ if (sdu_len)
sdu_len = 0;
- pdu_len += L2CAP_SDULEN_SIZE;
- }

if (len <= pdu_len) {
sar = L2CAP_SAR_END;
--
1.8.4

2014-08-13 17:27:21

by Marcel Holtmann

Subject: Re: [PATCH] Bluetooth: Improve data packing in SAR mode

Hi Lukasz,

> There is no need to decrease pdu size with L2CAP SDU lenght in Start
> L2CAP SDU frame. Start packtet is just 2 bytes longer as specified and
> we can keep payload as long as possible.
>
> Signed-off-by: Lukasz Rymanowski <[email protected]>
> ---
> When testing SAR L2CAP against PTS, L2CAP channel is usually
> configured in that way, that SDU = MPS * 3. PTS expets then 3
> I-Frames from IUT: Start, Continuation and End frame.
>
> Without this fix, we sent 4 I-Frames. We could pass a test
> by using -b option in l2test and send just two bytes less than
> SDU length but it was hakish :) With this patch no need to use -b
> option.
>
> net/bluetooth/l2cap_core.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel