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 E795CC433EF for ; Wed, 18 May 2022 10:12:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235005AbiERKMO (ORCPT ); Wed, 18 May 2022 06:12:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235026AbiERKMN (ORCPT ); Wed, 18 May 2022 06:12:13 -0400 Received: from relay10.mail.gandi.net (relay10.mail.gandi.net [IPv6:2001:4b98:dc4:8::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 181B254BE2; Wed, 18 May 2022 03:12:05 -0700 (PDT) Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 083F024000D; Wed, 18 May 2022 10:12:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1652868724; 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=zKOUE0TgP5jaR7ivGzIVvaKmVq+SAlnHg4cFTu46AG8=; b=dDyEqKE57zPFmAdYArPS75gz7yw066DLEznh5H32h54lkKQd84vj2AbX7xM5m8Ar8wUL8V JuC10JSafSQMlkSVAg4iAvlRsvwrPbEFwkzUVsR6Sd5vrjjeSGQBk3jt6hXRpVH6BET6BW cGznbrTjiznmDmSMHpNBWfcoHkh80SvlesD76nhf4gEg0mNJ62c77xRDQ2cwQLucz19q3H uH5KV8PXnTF+/B9Hqkf5GF1zl/SqkLBOhyZZ8F8RfO01lcMJnLowClu2HG2aiU0OlzkTWj zPaW2Sj01PR0QVTBuWtS+6MeqAd+f4UxBUIE0D3bzn6kLgkU1U75Ki9hY4DEbA== Date: Wed, 18 May 2022 12:12:00 +0200 From: Miquel Raynal To: Alexander Aring Cc: Alexander Aring , Stefan Schmidt , linux-wpan - ML , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Network Development , David Girault , Romuald Despres , Frederic Blain , Nicolas Schodet , Thomas Petazzoni Subject: Re: [PATCH wpan-next v2 09/11] net: mac802154: Introduce a synchronous API for MLME commands Message-ID: <20220518121200.2f08a6b1@xps-13> In-Reply-To: References: <20220512143314.235604-1-miquel.raynal@bootlin.com> <20220512143314.235604-10-miquel.raynal@bootlin.com> <20220517153045.73fda4ee@xps-13> Organization: Bootlin X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-wpan@vger.kernel.org aahringo@redhat.com wrote on Tue, 17 May 2022 21:14:03 -0400: > Hi, > > On Tue, May 17, 2022 at 9:30 AM Miquel Raynal wrote: > > > > > > aahringo@redhat.com wrote on Sun, 15 May 2022 19:03:53 -0400: > > > > > Hi, > > > > > > On Sun, May 15, 2022 at 6:28 PM Alexander Aring wrote: > > > > > > > > Hi, > > > > > > > > On Thu, May 12, 2022 at 10:34 AM Miquel Raynal > > > > wrote: > > > > > > > > > > This is the slow path, we need to wait for each command to be processed > > > > > before continuing so let's introduce an helper which does the > > > > > transmission and blocks until it gets notified of its asynchronous > > > > > completion. This helper is going to be used when introducing scan > > > > > support. > > > > > > > > > > Signed-off-by: Miquel Raynal > > > > > --- > > > > > net/mac802154/ieee802154_i.h | 1 + > > > > > net/mac802154/tx.c | 25 +++++++++++++++++++++++++ > > > > > 2 files changed, 26 insertions(+) > > > > > > > > > > diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h > > > > > index a057827fc48a..f8b374810a11 100644 > > > > > --- a/net/mac802154/ieee802154_i.h > > > > > +++ b/net/mac802154/ieee802154_i.h > > > > > @@ -125,6 +125,7 @@ extern struct ieee802154_mlme_ops mac802154_mlme_wpan; > > > > > void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb); > > > > > void ieee802154_xmit_sync_worker(struct work_struct *work); > > > > > int ieee802154_sync_and_hold_queue(struct ieee802154_local *local); > > > > > +int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *skb); > > > > > netdev_tx_t > > > > > ieee802154_monitor_start_xmit(struct sk_buff *skb, struct net_device *dev); > > > > > netdev_tx_t > > > > > diff --git a/net/mac802154/tx.c b/net/mac802154/tx.c > > > > > index 38f74b8b6740..ec8d872143ee 100644 > > > > > --- a/net/mac802154/tx.c > > > > > +++ b/net/mac802154/tx.c > > > > > @@ -128,6 +128,31 @@ int ieee802154_sync_and_hold_queue(struct ieee802154_local *local) > > > > > return ieee802154_sync_queue(local); > > > > > } > > > > > > > > > > +int ieee802154_mlme_tx(struct ieee802154_local *local, struct sk_buff *skb) > > > > > +{ > > > > > + int ret; > > > > > + > > > > > + /* Avoid possible calls to ->ndo_stop() when we asynchronously perform > > > > > + * MLME transmissions. > > > > > + */ > > > > > + rtnl_lock(); > > > > > > > > I think we should make an ASSERT_RTNL() here, the lock needs to be > > > > earlier than that over the whole MLME op. MLME can trigger more than > > > > > > not over the whole MLME_op, that's terrible to hold the rtnl lock so > > > long... so I think this is fine that some netdev call will interfere > > > with this transmission. > > > So forget about the ASSERT_RTNL() here, it's fine (I hope). > > > > > > > one message, the whole sync_hold/release queue should be earlier than > > > > that... in my opinion is it not right to allow other messages so far > > > > an MLME op is going on? I am not sure what the standard says to this, > > > > but I think it should be stopped the whole time? All those sequence > > > > > > Whereas the stop of the netdev queue makes sense for the whole mlme-op > > > (in my opinion). > > > > I might still implement an MLME pre/post helper and do the queue > > hold/release calls there, while only taking the rtnl from the _tx. > > > > And I might create an mlme_tx_one() which does the pre/post calls as > > well. > > > > Would something like this fit? > > I think so, I've heard for some transceiver types a scan operation can > take hours... but I guess whoever triggers that scan in such an > environment knows that it has some "side-effects"... Yeah, a scan requires the data queue to be stopped and all incoming packets to be dropped (others than beacons, ofc), so users must be aware of this limitation.