Re: [RFC PATCH 2/2] net: mac808211: mac802154: use lockdep_assert_in_softirq() instead own warning

Sebastian Andrzej Siewior
2018-05-04T19:08:06Z

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@linutronix.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)?

Sebastian