Re: [PATCH wpan-next v2 10/11] net: mac802154: Add a warning in the hot path

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Alexander Aring <aahringo@redhat.com>
Cc: Alexander Aring <alex.aring@gmail.com>,
	Stefan Schmidt <stefan@datenfreihafen.org>,
	linux-wpan - ML <linux-wpan@vger.kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Network Development <netdev@vger.kernel.org>,
	David Girault <david.girault@qorvo.com>,
	Romuald Despres <romuald.despres@qorvo.com>,
	Frederic Blain <frederic.blain@qorvo.com>,
	Nicolas Schodet <nico@ni.fr.eu.org>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Subject: Re: [PATCH wpan-next v2 10/11] net: mac802154: Add a warning in the hot path
Date: Tue, 17 May 2022 15:36:55 +0200	[thread overview]
Message-ID: <20220517153655.155ba311@xps-13> (raw)
In-Reply-To: <CAK-6q+jYb7A2RzG3u7PJYKZU9D5A=vben-Wnu-3EsUU-rqGT2Q@mail.gmail.com>

aahringo@redhat.com wrote on Sun, 15 May 2022 18:30:15 -0400:

> Hi,
> 
> On Thu, May 12, 2022 at 10:34 AM Miquel Raynal
> <miquel.raynal@bootlin.com> wrote:
> >
> > We should never start a transmission after the queue has been stopped.
> >
> > But because it might work we don't kill the function here but rather
> > warn loudly the user that something is wrong.
> >
> > Set an atomic when the queue will remain stopped. Reset this atomic when
> > the queue actually gets restarded. Just check this atomic to know if the
> > transmission is legitimate, warn if it is not.
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  include/net/cfg802154.h |  1 +
> >  net/mac802154/tx.c      | 16 +++++++++++++++-
> >  net/mac802154/util.c    |  1 +
> >  3 files changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
> > index 8b6326aa2d42..a1370e87233e 100644
> > --- a/include/net/cfg802154.h
> > +++ b/include/net/cfg802154.h
> > @@ -218,6 +218,7 @@ struct wpan_phy {
> >         struct mutex queue_lock;
> >         atomic_t ongoing_txs;
> >         atomic_t hold_txs;
> > +       atomic_t queue_stopped;  
> 
> Maybe some test_bit()/set_bit() is better there?

What do you mean? Shall I change the atomic_t type of queue_stopped?
Isn't the atomic_t preferred in this situation?