linux-kernel - Re: [RFC PATCH 2/2] net: mac808211: mac802154: use lockdep_assert_in

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Sat, 5 May 2018 09:06:58 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, tglx@...utronix.de,
        Ingo Molnar <mingo@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Johannes Berg <johannes@...solutions.net>,
        Alexander Aring <alex.aring@...il.com>,
        Stefan Schmidt <stefan@....samsung.com>,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        linux-wpan@...r.kernel.org,
        Anna-Maria Gleixner <anna-maria@...utronix.de>
Subject: Re: [RFC PATCH 2/2] net: mac808211: mac802154: use
 lockdep_assert_in_softirq() instead own warning


* Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote:

> On 2018-05-04 20:51:32 [+0200], Peter Zijlstra wrote:
> > On Fri, May 04, 2018 at 08:45:39PM +0200, Sebastian Andrzej Siewior wrote:
> > > On 2018-05-04 20:32:49 [+0200], Peter Zijlstra wrote:
> > > > On Fri, May 04, 2018 at 07:51:44PM +0200, Sebastian Andrzej Siewior wrote:
> > > > > From: Anna-Maria Gleixner <anna-maria@...utronix.de>
> > > > > 
> > > > > The warning in ieee802154_rx() and ieee80211_rx_napi() is there to ensure
> > > > > the softirq context for the subsequent netif_receive_skb() call. 
> > > > 
> > > > That's not in fact what it does though; so while that might indeed be
> > > > the intent that's not what it does.
> > > 
> > > It was introduced in commit d20ef63d3246 ("mac80211: document
> > > ieee80211_rx() context requirement"):
> > > 
> > >     mac80211: document ieee80211_rx() context requirement
> > >     
> > >     ieee80211_rx() must be called with softirqs disabled
> > 
> > softirqs disabled, ack that is exactly what it checks.
> > 
> > But afaict the assertion you introduced tests that we are _in_ softirq
> > context, which is not the same.
> 
> indeed, now it clicked. Given what I wrote in the cover letter would you
> be in favour of (a proper) lockdep_assert_BH_disabled() or the cheaper
> local_bh_enable() (assuming the network folks don't mind the cheaper
> version)?

BTW., going by the hardirq variant nomenclature:

        lockdep_assert_irqs_enabled();

... the proper name would not be lockdep_assert_BH_disabled(), but:

        lockdep_assert_softirqs_disabled();

Thanks,

	Ingo