Received-SPF: pass (google.com: best guess record for domain of linux-wireless-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <0b12af1b27954f62a5ce715f95176d1f0ff393a3.camel@sipsolutions.net>
Subject: Re: [RFCv3 3/3] nl80211: Send large new_wiphy events
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Denis Kenzior <denkenz@gmail.com>, linux-wireless@vger.kernel.org
Date:   Wed, 11 Sep 2019 17:12:11 +0200
In-Reply-To: <f48bdad3-f9f8-20b7-b6ff-6248368a7ae1@gmail.com> (sfid-20190911_161324_913292_899186EF)
References: <20190906154303.9303-1-denkenz@gmail.com>
         <20190906154303.9303-3-denkenz@gmail.com>
         <127c19b1855302a467a1bdbf2f25f625a0254d9e.camel@sipsolutions.net>
         <f48bdad3-f9f8-20b7-b6ff-6248368a7ae1@gmail.com>
         (sfid-20190911_161324_913292_899186EF)
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On Wed, 2019-09-11 at 07:20 -0500, Denis Kenzior wrote:

> > I'm not sure I see how the applications could do buffers that are
> > "inherently" large enough, there's no practical message size limit, is
> > there (32-bits for the size).
> 
> The kernel caps this to 32k right now if I read the code correctly.  But 
> fair point.

The kernel caps this for dumps only, no? We can allocate here ourselves
for multicasting a message as large as we like I think.

> > > +	if (WARN_ON(nl80211_send_wiphy(rdev, cmd, msg, 0, 0, 0, &state) < 0)) {
> > > +		nlmsg_free(msg);
> > > +		goto legacy;
> > > +	}
> > > +
> > > +	genlmsg_multicast_netns(&nl80211_fam, wiphy_net(&rdev->wiphy), msg, 0,
> > > +				NL80211_MCGRP_CONFIG2, GFP_KERNEL);
> > > +
> > > +legacy:
> > 
> > nit: just use "else" instead of the goto?
> 
> I'm not sure I understand?  We want to send both messages here...

It's equivalent to:

-----
if (WARN_ON(nl80211_send_wiphy(...) < 0)
   nlmsg_free(msg);
else
   genlmsg_multicast_netns(...);

... code for legacy ...
-----

no?

johannes