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Date: Wed, 19 Mar 2014 10:47:16 +0200
Message-ID: <CAB3XZEc0YpByFSu2QaPJ0VtACVRrJoQGfWKtC-qSPD1q1xKg1w@mail.gmail.com> (sfid-20140319_094722_812807_3633343D)
Subject: Re: [RFC 07/21] mac80211: improve find_chanctx() for reservations
From: Eliad Peller <eliad@wizery.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	Johannes Berg <johannes@sipsolutions.net>
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On Wed, Mar 19, 2014 at 10:34 AM, Michal Kazior <michal.kazior@tieto.com> wrote:
> On 18 March 2014 17:42, Eliad Peller <eliad@wizery.com> wrote:
>> On Tue, Mar 18, 2014 at 3:53 PM, Michal Kazior <michal.kazior@tieto.com> wrote:
>>> Relax ieee80211_find_chanctx(). If chanctx
>>> reservation chandef is compatible with
>>> current-future assigned interfaces chandef then
>>> allow it to be used by new interfaces.
>>>
>>> Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
>>> ---
>> [...]
>>
>>> +static const struct cfg80211_chan_def *
>>> +ieee80211_chanctx_reserved_chandef(struct ieee80211_local *local,
>>> +                                  struct ieee80211_chanctx *ctx,
>>> +                                  const struct cfg80211_chan_def *compat)
>>> +{
>>> +       struct ieee80211_sub_if_data *sdata;
>>> +
>>> +       lockdep_assert_held(&local->chanctx_mtx);
>>> +
>>> +       list_for_each_entry(sdata, &ctx->reserved_vifs,
>>> +                           reserved_chanctx_list) {
>>> +               if (!compat)
>>> +                       compat = &sdata->reserved_chandef;
>> this check is redundant.
>
> It isn't. The function can be called with compat == NULL. You don't
> want to call cfg80211_chandef_compatible() with a NULL chandef.
>
at least this patch has an explicit check for compat not being NULL
(before calling the function).
since this function checks chandef compatibility with current
reserved chandefs, i don't see why anyone would call it with NULL?

Eliad.