[Click] How to write to /proc in a click element

[Javier Sánchez]

ok change the channel at ieee80211_hardstart() when the TX queues
initialize no problem.

But u can change the channel per packet basis? i think this is not
possible, to change the channel the drivers needs to reset the chip
and restart the tx queues. It is not like change the rate , or the
retries..  which can be made per packet basis.

But certainly i not tried or worked at it, may be i am wrong.

Regards
Javier

2009/7/27 Robert Sombrutzki <sombrutz at informatik.hu-berlin.de>:
> Hi Javier,
> i set the channel in ieee80211_hardstart() before ieee80211_monitor_encap() is
> called:
>
> if (vap->iv_opmode == IEEE80211_M_MONITOR) {
>  if ( ( (vap->iv_flags_ext & IEEE80211_FEXT_CHANNELSWITCH) != 0 ) && (
> skb->dev->type == ARPHRD_IEEE80211_ATHDESC2 ) )
>  {
>   /*I edit the current channel structure, the other option is to create new
> structure*/
>   chan = ic->ic_curchan;
>   ath2_h = ( struct ath2_header*)(skb->data + ATHDESC_HEADER_SIZE);
>
>   if ( ( ath2_h->anno.tx_anno.channel != 0 ) && (
> ath2_h->anno.tx_anno.channel != chan->ic_ieee ) ) {
>      //printk("channelswitch: %d
> to %d\n",chan->ic_ieee,ath2_h->anno.tx_anno.channel);
>      chan->ic_ieee = ath2_h->anno.tx_anno.channel;
>      chan->ic_freq = ieee80211_ieee2mhz( chan->ic_ieee , chan->ic_flags);
>      //see ieee80211_input.c and what is done here
>     ic->ic_set_channel(ic);
>   }
>   /*end of channel switching*/
>  }
>
>  ieee80211_monitor_encap(vap, skb);
>  ieee80211_parent_queue_xmit(skb);
>  return NETDEV_TX_OK;
> }
>
> I add a new header-type (ATHDESC2), which is nearly the same as athdesc, but
> with some extention. IEEE80211_FEXT_CHANNELSWITCH is related to a sysctl,
> which i add to control the feature (enable/disable).
>
> Regards
> Robert
>
> On Montag, 27. Juli 2009, Javier Sánchez wrote:
>> Hi Robert,
>>
>> Are u sure on this?
>>
>> Packets for monitor device comes from ieee80211_output.c ->
>> ieee80211_monitor_encap()
>>
>> on this function the channel value is not processed into
>> ieee80211_phy_params ph, for example:
>>
>> rate is processed:
>>
>> case IEEE80211_RADIOTAP_RATE:
>> ph->rate0 = *p;
>> p++;
>> break;
>>
>>
>> channel is not processed:
>>
>> case IEEE80211_RADIOTAP_CHANNEL:
>> /* 2 x 16-bit */
>> p = start + roundup(p - start, 2) + 4;
>> break;
>>
>> Regards
>> Javier
>>
>>
>> On Mon, Jul 27, 2009 at 5:49 PM, Robert
>>
>> Sombrutzki<sombrutz at informatik.hu-berlin.de> wrote:
>> > Hi,
>> > i think, it's not the best way to use a sysctl to set the channel,
>> > because you can not control which packets are sent on which channel,
>> > since you have several queues. Example: you have packet a and b , you
>> > want to sent packet a on channel 1 and b on 2. How do you want to control
>> > that the new channel is set between these two packets ? Of course, you
>> > can delay packet b until the new channel is set, but that has no good
>> > performance. I think it better to set the channel using an annotation on
>> > the packet. You can extend the ath-header (use AthdescEncap) with an
>> > extra field for the channel, which should used for the packet. In the
>> > madwifi-driver (e.g. in
>> > ieee80211_output.c), you check for the encap-type, the field in the
>> > header and the channel and switch to the new channel ( struct
>> > ieee80211com includes pointer to the channel-switch-function:
>> > ic_set_channel). The problem here is, that you have to sent a packet to
>> > switch the channel, but therefor it is precise. To switch the channel
>> > without transmitting a packet, you can generate a packet which just
>> > initiates the changing the channel, but which is discard by the driver
>> > afterwards. According to the channel you can mark such kind of packets
>> > using an extention to the ath-header.
>> > I use this solution and it works well.
>> >
>> > Regards,
>> > Robert
>> >
>> >>Hi,
>> >>
>> >>Can someone please advise me how to write something in /proc/sys in a
>> >> click event? I need to change the channel in MadWifi upon reception of a
>> >> control packet. I am planning on writing a sysctl handler in madwifi to
>> >> change the channel upon request, and I need to trigger it using Click.
>> >> If someone has a better suggestion to do this - I'll be glad to know!
>> >>
>> >>Thanks for your help and time.
>> >>
>> >>Ashish
>> >
>> > _______________________________________________
>> > click mailing list
>> > click at amsterdam.lcs.mit.edu
>> > https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>
>
>