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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 D2759C433B4 for ; Mon, 10 May 2021 20:56:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A64D1611CA for ; Mon, 10 May 2021 20:56:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232774AbhEJU56 (ORCPT ); Mon, 10 May 2021 16:57:58 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:58198 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232082AbhEJU55 (ORCPT ); Mon, 10 May 2021 16:57:57 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 0BC601C0B76; Mon, 10 May 2021 22:56:51 +0200 (CEST) Date: Mon, 10 May 2021 22:56:50 +0200 From: Pavel Machek To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Bhaumik Bhatt , Hemant Kumar , Manivannan Sadhasivam Subject: Re: [PATCH 5.10 002/299] bus: mhi: core: Clear configuration from channel context during reset Message-ID: <20210510205650.GA17966@amd> References: <20210510102004.821838356@linuxfoundation.org> <20210510102004.900838842@linuxfoundation.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="TB36FDmn/VVEgNH/" Content-Disposition: inline In-Reply-To: <20210510102004.900838842@linuxfoundation.org> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --TB36FDmn/VVEgNH/ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > From: Bhaumik Bhatt >=20 > commit 47705c08465931923e2f2b506986ca0bdf80380d upstream. >=20 > When clearing up the channel context after client drivers are > done using channels, the configuration is currently not being > reset entirely. Ensure this is done to appropriately handle > issues where clients unaware of the context state end up calling > functions which expect a context. > +++ b/drivers/bus/mhi/core/init.c > @@ -544,6 +544,7 @@ void mhi_deinit_chan_ctxt(struct mhi_con > + u32 tmp; > @@ -554,7 +555,19 @@ void mhi_deinit_chan_ctxt(struct mhi_con =2E.. > + tmp =3D chan_ctxt->chcfg; > + tmp &=3D ~CHAN_CTX_CHSTATE_MASK; > + tmp |=3D (MHI_CH_STATE_DISABLED << CHAN_CTX_CHSTATE_SHIFT); > + chan_ctxt->chcfg =3D tmp; > + > + /* Update to all cores */ > + smp_wmb(); > } This is really interesting code; author was careful to make sure chcfg is updated atomically, but C compiler is free to undo that. Plus, this will make all kinds of checkers angry. Does the file need to use READ_ONCE and WRITE_ONCE? Best regards, Pavel --=20 DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --TB36FDmn/VVEgNH/ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAmCZnhIACgkQMOfwapXb+vLm+QCgrjtqO/fk9hdWsOqd82lCs93/ OkAAoJT5b/Oi5j5XtOKXCYwDFMuvzCYA =NHPs -----END PGP SIGNATURE----- --TB36FDmn/VVEgNH/--