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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 16349C433E3 for ; Mon, 22 Mar 2021 11:56:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3D8B6199E for ; Mon, 22 Mar 2021 11:56:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230232AbhCVL4B (ORCPT ); Mon, 22 Mar 2021 07:56:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230134AbhCVLzl (ORCPT ); Mon, 22 Mar 2021 07:55:41 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 96A88C061574 for ; Mon, 22 Mar 2021 04:55:41 -0700 (PDT) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lOJ9l-0001wO-R7; Mon, 22 Mar 2021 12:55:37 +0100 Received: from ukl by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1lOJ9k-0002yG-AV; Mon, 22 Mar 2021 12:55:36 +0100 Date: Mon, 22 Mar 2021 12:55:36 +0100 From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= To: Sebastian Andrzej Siewior Cc: Johan Hovold , 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: <20210322115536.knkea7i6vrfpotol@pengutronix.de> References: <20210322111036.31966-1-johan@kernel.org> <20210322113402.naqzgkoe2xesnw4b@pengutronix.de> <20210322113918.ze52gq54cpsspgej@linutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="7izeeft7juynhm6v" Content-Disposition: inline In-Reply-To: <20210322113918.ze52gq54cpsspgej@linutronix.de> X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --7izeeft7juynhm6v Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hallo Sebastian, 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=F6nig wrote: > > On Mon, Mar 22, 2021 at 12:10:36PM +0100, Johan Hovold wrote: > > > Force-threaded interrupt handlers used to run with interrupts enabled, > > > something which could lead to deadlocks in case a threaded handler > > > shared a lock with code running in hard interrupt context (e.g. timer > > > 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. The commit log says essentially: "The change is fine on non-RT" which suggests there is a problem on RT. So something like: On non-RT interrupts are disabled also for force threaded handlers (since commit 81e2073c175b ...). On RT there is no problem either because ... So we don't need to handle this case in the driver any more. would be preferable. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig | Industrial Linux Solutions | https://www.pengutronix.de/ | --7izeeft7juynhm6v Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAmBYhbUACgkQwfwUeK3K 7AkgqAgAgTgdaglMq9hbZzRXzVYb3dpQz/Wevwb7A3UCS5godfj5mzrFMKzUWz16 MkcP7qv5pbyj5xvK4HgZWhE06mPXkR3k/H3B8yeCNG00TUe5SDM1sPbKPZLc2SzI uRzU0ImeVHodghGBuYKRUqEiSliwCGJzUBZFZc5Ij5tfNgXvk0kXNdxnWX7d3NzQ i23EdTPCDBAxSl1CmkjocnP8o9lEbBIOSVtXE8PBWKmiqqOM03xn8NsJcuTTuTji CkNlkvpU/QgA+/Un0fSq/gflti8zkVFz0GJFqcR5OFysAcfsIu8uc2zpcoP8aXvZ mERj0gQCekf6AzoeYALL2uOWeDbyRA== =ZyzD -----END PGP SIGNATURE----- --7izeeft7juynhm6v--