[PATCH 1/2] supplicant: Use high-priority queue for management packets.

[Ben Greear]

Any more thought on this?



On 09/23/2013 09:04 AM, Ben Greear wrote:
> On 09/23/2013 01:08 AM, Jouni Malinen wrote:
>> On Mon, Sep 09, 2013 at 11:49:04AM -0700, greearb at candelatech.com wrote:
>>> Without this patch, wpa_supplicant EAPOL packets (at least)
>>> are sent on normal best-effort TX queue.  I believe they
>>> should be on the VO high-priority queue instead.
>>
>>> diff --git a/src/l2_packet/l2_packet_linux.c b/src/l2_packet/l2_packet_linux.c
>>
>>> @@ -97,6 +97,7 @@ struct l2_packet_data * l2_packet_init(
>>> +    /* Use high-priority queue for management packets
>>> +     * http://wireless.kernel.org/en/developers/Documentation/mac80211/queues
>>> +     */
>>> +    if (setsockopt(l2->fd, SOL_SOCKET,
>>> +               SO_PRIORITY, (char*)&val, sizeof(val)) < 0) {
>>
>> This seems to be assuming that mac80211 is used always. That is not
>> really the case and I guess this SO_PRIORITY change to a special
>> mac80211-specific value could result in undesired results with
>> non-mac80211 drivers.
>
> The special priority is defined in the net/wireless/ dir of the kernel,
> and does not make special mention of mac80211 v/s other logic.
>
>  From what I can tell, there is no other way to specify QoS when
> sending on packet-sockets.  The skb->priority never hits the wire
> directly, so either something should be using it properly, or it
> will just be ignored and we are no worse off than before.  If
> some driver is actually conflicting with the documentation, then
> we just need to fix it.
>
> from net/wireless/util.c:
>
> /* Given a data frame determine the 802.1p/1d tag to use. */
> unsigned int cfg80211_classify8021d(struct sk_buff *skb)
> {
>      unsigned int dscp;
>
>      /* skb->priority values from 256->263 are magic values to
>       * directly indicate a specific 802.1d priority.  This is used
>       * to allow 802.1d priority to be passed directly in from VLAN
>       * tags, etc.
>       */
>      if (skb->priority >= 256 && skb->priority <= 263)
>          return skb->priority - 256;
>
>      switch (skb->protocol) {
>      case htons(ETH_P_IP):
>          dscp = ipv4_get_dsfield(ip_hdr(skb)) & 0xfc;
>          break;
>      case htons(ETH_P_IPV6):
>          dscp = ipv6_get_dsfield(ipv6_hdr(skb)) & 0xfc;
>          break;
>      default:
>          return 0;
>      }
>
>      return dscp >> 5;
> }
> EXPORT_SYMBOL(cfg80211_classify8021d);
>
>
> Thanks,
> Ben
>


-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com