From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11B1DC433F5 for ; Thu, 28 Apr 2022 07:59:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343668AbiD1ICS (ORCPT ); Thu, 28 Apr 2022 04:02:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343692AbiD1ICI (ORCPT ); Thu, 28 Apr 2022 04:02:08 -0400 Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4437820BCE; Thu, 28 Apr 2022 00:58:53 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id AF8451C0003; Thu, 28 Apr 2022 07:58:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1651132731; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=3wu9h3NKSKmvHgwXQf+X1OC4mECGCeu1/MQPJ6QY6SE=; b=bijCSztHgJJMugFQFHiUQ8aYuRkjruUCYnmB0kgjbJAB1EEdR4wYJf/Y0mbA+kgCGF7JDE I/iYOiYIB8edk+3JyFYwuGrJtngst0ToSfMzvrBg9TpRnxazbFPe24IHBcrHqGYbkKnwzJ AmoRy/5ozhvOXJYSLEMTxBnTDuuhWqOnFEpFGe+CaZspKLXsYEOuRRSHA7ajdmvRI6UTIu YnzzEjZsG8UwGxkKMTAxiAJciDyFnbE/CbyVMQe/a09ZEm0kffvG5ewYVmmPyKNOmpHxT5 1fERTsbKynD+H9DtSoJSXV5e0lcbuNApL0mADhbfu6iecEqiaOEAKoS7S4O0zQ== Date: Thu, 28 Apr 2022 09:58:48 +0200 From: Miquel Raynal To: Alexander Aring Cc: Stefan Schmidt , linux-wpan - ML , "David S. Miller" , Jakub Kicinski , "open list:NETWORKING [GENERAL]" , David Girault , Romuald Despres , Frederic Blain , Nicolas Schodet , Thomas Petazzoni Subject: Re: [PATCH wpan-next 08/11] net: mac802154: Add a warning in the hot path Message-ID: <20220428095848.34582df4@xps13> In-Reply-To: References: <20220427164659.106447-1-miquel.raynal@bootlin.com> <20220427164659.106447-9-miquel.raynal@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.7 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-wpan@vger.kernel.org Hi Alexander, alex.aring@gmail.com wrote on Wed, 27 Apr 2022 14:01:25 -0400: > Hi, >=20 > On Wed, Apr 27, 2022 at 12:47 PM Miquel Raynal > 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. > > > > Signed-off-by: Miquel Raynal > > --- [...] > > diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c > > index a8a83f0167bf..021dddfea542 100644 > > --- a/net/mac802154/tx.c > > +++ b/net/mac802154/tx.c > > @@ -124,6 +124,8 @@ bool ieee802154_queue_is_held(struct ieee802154_loc= al *local) > > static netdev_tx_t > > ieee802154_hot_tx(struct ieee802154_local *local, struct sk_buff *skb) > > { > > + WARN_ON_ONCE(ieee802154_queue_is_stopped(local)); > > + > > return ieee802154_tx(local, skb); > > } > > > > diff --git a/net/mac802154/util.c b/net/mac802154/util.c > > index 847e0864b575..cfd17a7db532 100644 > > --- a/net/mac802154/util.c > > +++ b/net/mac802154/util.c > > @@ -44,6 +44,24 @@ void ieee802154_stop_queue(struct ieee802154_local *= local) > > rcu_read_unlock(); > > } > > > > +bool ieee802154_queue_is_stopped(struct ieee802154_local *local) > > +{ > > + struct ieee802154_sub_if_data *sdata; > > + bool stopped =3D true; > > + > > + rcu_read_lock(); > > + list_for_each_entry_rcu(sdata, &local->interfaces, list) { > > + if (!sdata->dev) > > + continue; > > + > > + if (!netif_queue_stopped(sdata->dev)) > > + stopped =3D false; > > + } > > + rcu_read_unlock(); > > + > > + return stopped; > > +} =20 >=20 > sorry this makes no sense, you using net core functionality to check > if a queue is stopped in a net core netif callback. Whereas the sense > here for checking if the queue is really stopped is when 802.15.4 > thinks the queue is stopped vs net core netif callback running. It > means for MLME-ops there are points we want to make sure that net core > is not handling any xmit and we should check this point and not > introducing net core functionality checks. I think I've mixed two things, your remark makes complete sense. I should instead here just check a 802.15.4 internal variable. > btw: if it's hit your if branch the first time you can break? Yes, we could definitely improve a bit the logic to break earlier, but in the end these checks won't remain I believe. > I am not done with the review, this is just what I see now and we can > discuss that. Please be patient. Sure, thanks for the quick feedback anyway! hanks, Miqu=C3=A8l