DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 51D0D20651
To:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
From:   Ben Greear <greearb@candelatech.com>
Subject: Should we check netif_running in cfg80211_calculate_bi_data?
Organization: Candela Technologies
Message-ID: <8c876445-a065-ddb2-4dcf-e922f22a1b7d@candelatech.com>
Date:   Mon, 22 Oct 2018 13:27:53 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

I was testing on my 4.16 kernel with a bunch of VAPs and I had two configured
for 100 beacon interval, and more at 240.  This failed for reasons I figured out
(gcd logic), but even once I tried to configure the vaps for 240 interval they
could not come up.  I am thinking maybe it was because I could only re-configure
admin-up interfaces, and they couldn't come up due the gcd thing?

Anyway, while poking, I thought maybe the patch below would be helpful since
we shouldn't care about admin-down interfaces in this case?

diff --git a/net/wireless/util.c b/net/wireless/util.c
index fbc880e..56d7583 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1541,6 +1541,9 @@ static void cfg80211_calculate_bi_data(struct wiphy *wiphy, u32 new_beacon_int,
                 if (wdev->beacon_interval == *beacon_int_gcd)
                         continue;

+               if (!netif_running(wdev->netdev))
+                       continue;
+
                 *beacon_int_different = true;
                 *beacon_int_gcd = gcd(*beacon_int_gcd, wdev->beacon_interval);
         }

Thanks,
Ben

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