> Oh, I misread the code. I thought it was only looking for a
> user-specified BSSID (but I had not specified one). Actually it is
> checking that we aren't attempting to join the same network that we are
> already on.
>
> The problem that was preventing me from getting connectivity was
> channel. It was only accepting IBSSes on local->hw.conf.channel, so I
> was required to do "iwconfig wlan0 channel X" first.
Heh. I might have done that, yeah.
> Is this by design, or is automatic channel selection a desirable
> feature? see attached patch, which seems to be working
Seems we should do automatic selection, the patch looks ok to me.
I wonder though, if we decide to create a new IBSS, which channel will
we choose?
> Daniel
> plain text document attachment (ibss-channel.txt)
> [PATCH] mac80211: automatic IBSS channel selection
>
> When joining an ad-hoc network, the user is currently required to specify
> the channel. The network will not be joined otherwise, unless it happens
> to be sitting on the currently active channel.
>
> This patch implements automatic channel selection when the user has not
> locked the interface onto a specific channel.
>
> Signed-off-by: Daniel Drake <dsd@xxxxxxxxxx>
Acked-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
>
> Index: linux-2.6.26-rc8/net/mac80211/mlme.c
> ===================================================================
> --- linux-2.6.26-rc8.orig/net/mac80211/mlme.c
> +++ linux-2.6.26-rc8/net/mac80211/mlme.c
> @@ -3582,6 +3582,7 @@ static int ieee80211_sta_find_ibss(struc
> int found = 0;
> u8 bssid[ETH_ALEN];
> int active_ibss;
> + int search_freq;
> DECLARE_MAC_BUF(mac);
> DECLARE_MAC_BUF(mac2);
>
> @@ -3614,11 +3615,21 @@ static int ieee80211_sta_find_ibss(struc
> printk(KERN_DEBUG " sta_find_ibss: selected %s current "
> "%s\n", print_mac(mac, bssid), print_mac(mac2, ifsta->bssid));
> #endif /* CONFIG_MAC80211_IBSS_DEBUG */
> - if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0 &&
> - (bss = ieee80211_rx_bss_get(dev, bssid,
> - local->hw.conf.channel->center_freq,
> - ifsta->ssid, ifsta->ssid_len))) {
> +
> + if (found && memcmp(ifsta->bssid, bssid, ETH_ALEN) != 0) {
> int ret;
> + int search_freq;
> +
> + if (ifsta->flags & IEEE80211_STA_AUTO_CHANNEL_SEL)
> + search_freq = bss->freq;
> + else
> + search_freq = local->hw.conf.channel->center_freq;
> +
> + bss = ieee80211_rx_bss_get(dev, bssid, search_freq,
> + ifsta->ssid, ifsta->ssid_len);
> + if (!bss)
> + goto dont_join;
> +
> printk(KERN_DEBUG "%s: Selected IBSS BSSID %s"
> " based on configured SSID\n",
> dev->name, print_mac(mac, bssid));
> @@ -3626,6 +3637,8 @@ static int ieee80211_sta_find_ibss(struc
> ieee80211_rx_bss_put(dev, bss);
> return ret;
> }
> +
> +dont_join:
> #ifdef CONFIG_MAC80211_IBSS_DEBUG
> printk(KERN_DEBUG " did not try to join ibss\n");
> #endif /* CONFIG_MAC80211_IBSS_DEBUG */
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