[Ieee80211-devel] [RFC] remove ieee80211_classify(skb)

[ashwin c. <ash...@gm...>]

The generic ieee80211 network stack in 2.6.18 (vanilla) has a call to
ieee80211_classify(skb) in its xmit routine.
If I understand this right, then this routine maps the ToS field to
802.1Dprio. (?)
and then sets the header's qos_ctl accordingly to signify QoS data or QoS
NULL.

But, the xmit routine also accepts a prio parameter which is passed on, as
is, to the low level device drivers hard_xmit.
Looking at my ipw2200 driver, I find that this prio value is used to map to
the appropriate h/w queues, with the assumption that its value is already a
802.1D prio.

So my suggestion is that we need not do the classification
(ieee80211_classify) in the stack, at least at the point where it is right
now. As long as the priority value that comes in the xmit function of the
stack is non-zero, header->qos_ctl != NULL.

In any case for apps that mangle the ToS field for their QoS requirements,
the mapping from ToS to 1D prio can be done elsewhere ( pardon the
uncertainty here, I'm quite the novice). :)


Cheers,

Ashwin



Signed-off-by: Ashwin Chaugule <ash...@gm...>

--

--- ieee80211_tx.c-orig    2006-10-25 20:24:09.000000000 +0530
+++ ieee80211_tx.c    2006-10-25 20:27:02.000000000 +0530
@@ -219,35 +219,6 @@
     return txb;
 }

-static int ieee80211_classify(struct sk_buff *skb)
-{
-    struct ethhdr *eth;
-    struct iphdr *ip;
-
-    eth = (struct ethhdr *)skb->data;
-    if (eth->h_proto != __constant_htons(ETH_P_IP))
-        return 0;
-
-    ip = skb->nh.iph;
-    switch (ip->tos & 0xfc) {
-    case 0x20:
-        return 2;
-    case 0x40:
-        return 1;
-    case 0x60:
-        return 3;
-    case 0x80:
-        return 4;
-    case 0xa0:
-        return 5;
-    case 0xc0:
-        return 6;
-    case 0xe0:
-        return 7;
-    default:
-        return 0;
-    }
-}

 /* Incoming skb is converted to a txb which consists of
  * a block of 802.11 fragment packets (stored as skbs) */
@@ -335,9 +306,8 @@
     if (ieee->is_qos_active && ieee->is_qos_active(dev, skb)) {
         fc |= IEEE80211_STYPE_QOS_DATA;
         hdr_len += 2;
-
-        skb->priority = ieee80211_classify(skb);
-        header.qos_ctl |= cpu_to_le16(skb->priority & IEEE80211_QCTL_TID);
+        if (priority <= 7)
+            header.qos_ctl |= cpu_to_le16(skb->priority &
IEEE80211_QCTL_TID);
     }
     header.frame_ctl = cpu_to_le16(fc);


--