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 X-Spam-Level: X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6179C433C1 for ; Mon, 22 Mar 2021 13:24:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A813E61925 for ; Mon, 22 Mar 2021 13:24:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230108AbhCVNYM (ORCPT ); Mon, 22 Mar 2021 09:24:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:39092 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231558AbhCVNVg (ORCPT ); Mon, 22 Mar 2021 09:21:36 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 63D5C61920; Mon, 22 Mar 2021 13:20:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616419240; bh=PylH9sPq+BiwMbT0thhLCmMC0c6t2G8e8YGKgsiPnLc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AYCLSONFzvNSVaw41M2y2xFnqh1hsZTFDEV8wMnbTQmfxFz4LrP31W/xxXehUsvf5 iZCrF7ak/MBjQcYnZufREQREBuGHM/V2vQIrK0b17miNYzllzE4SoGVhpicSQC3YJn epK31IgEl5qlg0AbLGZ13GI2w3QYXgDLmTpZk3msNgf4Sc6uMxVhray7AdTudjPDRb 2gfpsQrE1I2xlY6GWVCch+/wspNVOzuVufytf0V+Jt5ODv86PjpkeF/hCioR+C4D+O GnWnkTB9dPiTvsivmNv6hhaV6FQkrosGrgA9Hv0FJ7viact+ZAZXXdzoMWNzWq4nz/ O+45P6mSKQf8g== Received: from johan by xi with local (Exim 4.93.0.4) (envelope-from ) id 1lOKUL-0008Jm-Pp; Mon, 22 Mar 2021 14:20:57 +0100 Date: Mon, 22 Mar 2021 14:20:57 +0100 From: Johan Hovold To: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= Cc: Sebastian Andrzej Siewior , Greg Kroah-Hartman , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Sam Nobs , Thomas Gleixner , Peter Zijlstra Subject: Re: [PATCH] serial: imx: drop workaround for forced irq threading Message-ID: References: <20210322111036.31966-1-johan@kernel.org> <20210322113402.naqzgkoe2xesnw4b@pengutronix.de> <20210322113918.ze52gq54cpsspgej@linutronix.de> <20210322115536.knkea7i6vrfpotol@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0amXQDi444UcwEvd" Content-Disposition: inline In-Reply-To: <20210322115536.knkea7i6vrfpotol@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --0amXQDi444UcwEvd Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Mar 22, 2021 at 12:55:36PM +0100, Uwe Kleine-K=C3=B6nig wrote: > Hallo Sebastian, >=20 > On Mon, Mar 22, 2021 at 12:39:18PM +0100, Sebastian Andrzej Siewior wrote: > > On 2021-03-22 12:34:02 [+0100], Uwe Kleine-K=C3=B6nig wrote: > > > On Mon, Mar 22, 2021 at 12:10:36PM +0100, Johan Hovold wrote: > > > > Force-threaded interrupt handlers used to run with interrupts enabl= ed, > > > > something which could lead to deadlocks in case a threaded handler > > > > shared a lock with code running in hard interrupt context (e.g. tim= er > > > > callbacks) and did not explicitly disable interrupts. > > > >=20 > > > > This was specifically the case for serial drivers that take the port > > > > lock in their console write path as printk can be called from hard > > > > interrupt context also with forced threading ("threadirqs"). > > > >=20 > > > > Since commit 81e2073c175b ("genirq: Disable interrupts for force > > > > threaded handlers") interrupt handlers always run with interrupts > > > > disabled on non-RT so that drivers no longer need to do handle this. > > >=20 > > > So we're breaking RT knowingly here? If this is the case I'm not happy > > > with your change. (And if RT is not affected a different wording would > > > be good.) > >=20 > > Which wording, could you be more specific? It looks good from here and > > no, RT is not affected. >=20 > The commit log says essentially: "The change is fine on non-RT" which > suggests there is a problem on RT. I don't think you can read that into the commit message. Why would I knowingly break RT? And why would RT depend on patching individual serial drivers in the first place? That interrupt handlers run with interrupts enabled in RT is kind of given. The unfortunate (buggy) bit was that they weren't always disabled for non-RT. Johan --0amXQDi444UcwEvd Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQQHbPq+cpGvN/peuzMLxc3C7H1lCAUCYFiZtAAKCRALxc3C7H1l CC3MAPsFP38oaSUs2lUB7Pb8F2VVx63qwxHSI2Aq5/pY1DMu5wEA/bbSGqHCYRo2 4iL/3EZSKQ61BpMwYxg1MbK0rCyPxAo= =vSUx -----END PGP SIGNATURE----- --0amXQDi444UcwEvd--