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 2538DC4321E for ; Mon, 5 Dec 2022 09:05:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230252AbiLEJFd (ORCPT ); Mon, 5 Dec 2022 04:05:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232523AbiLEJES (ORCPT ); Mon, 5 Dec 2022 04:04:18 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51960BF6E for ; Mon, 5 Dec 2022 01:04:12 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DA59760FDE for ; Mon, 5 Dec 2022 09:04:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF379C433D7; Mon, 5 Dec 2022 09:04:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670231051; bh=bENrYC1DUTi7/2KslKN/oLUt/KX6fo/YMhSWxvmhlaw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZL43+Lq34QOg/cUthOBkNfdFvVxoqsstjEkm5gMcUEF03/Nrqx0mHux/j/9fxEMuZ Huzet9AsWE4xdhPoj+UguELC+L6mprvVsSOLB1dIsz0OYAhgmBu2conyuUOWS9oDWG fhNscjeuOmsHaTYTF3ofeN8mGq8r9HQjxfRE2Q3fWjjiwb0pcJXMTfzxFfOe0gBpiQ 9cIzoinnhF38qU1kqqk+xjZKPg8KkpBZ6u1C7DIWPlmIt3FliJ3SWYyylXh1gfDqwt 0WG+JRXi4kYYyka2D+fMvWPOivJqn+VdV09rJJJFPPk4/IiT1rn+p3onfLCRQcWTNk k+gbEuaJkqc2g== Date: Mon, 5 Dec 2022 10:04:07 +0100 From: Lorenzo Bianconi To: Leon Romanovsky Cc: netdev@vger.kernel.org, nbd@nbd.name, john@phrozen.org, sean.wang@mediatek.com, Mark-MC.Lee@mediatek.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, matthias.bgg@gmail.com, linux-mediatek@lists.infradead.org, lorenzo.bianconi@redhat.com Subject: Re: [PATCH net-next] net: ethernet: mtk_wed: fix possible deadlock if mtk_wed_wo_init fails Message-ID: References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="b7kiYn5Wg7Rk9JEy" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --b7kiYn5Wg7Rk9JEy Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Dec 05, Leon Romanovsky wrote: > On Sun, Dec 04, 2022 at 04:09:21PM +0100, Lorenzo Bianconi wrote: > > > On Fri, Dec 02, 2022 at 06:36:33PM +0100, Lorenzo Bianconi wrote: > > > > Introduce __mtk_wed_detach() in order to avoid a possible deadlock = in > > > > mtk_wed_attach routine if mtk_wed_wo_init fails. > > > >=20 > > > > Fixes: 4c5de09eb0d0 ("net: ethernet: mtk_wed: add configure wed wo = support") > > > > Signed-off-by: Lorenzo Bianconi > > > > --- > > > > drivers/net/ethernet/mediatek/mtk_wed.c | 24 ++++++++++++++---= ---- > > > > drivers/net/ethernet/mediatek/mtk_wed_mcu.c | 10 ++++++--- > > > > drivers/net/ethernet/mediatek/mtk_wed_wo.c | 3 +++ > > > > 3 files changed, 26 insertions(+), 11 deletions(-) > > >=20 > > > <...> > > >=20 > > > > diff --git a/drivers/net/ethernet/mediatek/mtk_wed_mcu.c b/drivers/= net/ethernet/mediatek/mtk_wed_mcu.c > > > > index f9539e6233c9..b084009a32f9 100644 > > > > --- a/drivers/net/ethernet/mediatek/mtk_wed_mcu.c > > > > +++ b/drivers/net/ethernet/mediatek/mtk_wed_mcu.c > > > > @@ -176,6 +176,9 @@ int mtk_wed_mcu_send_msg(struct mtk_wed_wo *wo,= int id, int cmd, > > > > u16 seq; > > > > int ret; > > > > =20 > > > > + if (!wo) > > > > + return -ENODEV; > > >=20 > > > <...> > > >=20 > > > > static void > > > > mtk_wed_wo_hw_deinit(struct mtk_wed_wo *wo) > > > > { > > > > + if (!wo) > > > > + return; > > >=20 > > > How are these changes related to the written in deadlock? > > > How is it possible to get internal mtk functions without valid wo? > >=20 > > Hi Leon, > >=20 > > if mtk_wed_rro_alloc() fails in mtk_wed_attach(), we will end up running > > __mtk_wed_detach() when wo struct is not allocated yet (wo is allocated= in > > mtk_wed_wo_init()). >=20 > IMHO, it is a culprit, proper error unwind means that you won't call to > uninit functions for something that is not initialized yet. It is better > to fix it instead of adding "if (!wo) ..." checks. So, iiuc, you would prefer to do something like: __mtk_wed_detach() { ... if (mtk_wed_get_rx_capa(dev) && wo) { mtk_wed_wo_reset(dev); mtk_wed_free_rx_rings(dev); mtk_wed_wo_deinit(hw); } ... =09 Right? I am fine both ways :) >=20 > > Moreover __mtk_wed_detach() can run mtk_wed_wo_reset() and mtk_wed_wo_d= einit() >=20 > This is another side of same coin. If you can run them in parallel, you > need locking protection and ability to cancel work, so nothing is going > to be executed once cleanup succeeded. Sorry, I did not get what you mean here with 'in parallel'. __mtk_wed_detac= h() always run with hw_lock mutex help in both mtk_wed_attach() or mtk_wed_detach(). Regards, Lorenzo >=20 > These were my 2 cents, totally IMHO. >=20 > Thanks --b7kiYn5Wg7Rk9JEy Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCY420BwAKCRA6cBh0uS2t rP7CAQCPV9L7X9gyMO52Hg3Vpt1Z75bnZXcBgH59ibA6g58pYAD/XNFOw9soq3Jx MzkDWh5S2ZvFTFPXP7n4sxpJ+HAbMwE= =n8lE -----END PGP SIGNATURE----- --b7kiYn5Wg7Rk9JEy--