From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753542AbeDYWIk (ORCPT ); Wed, 25 Apr 2018 18:08:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:38136 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752313AbeDYWIj (ORCPT ); Wed, 25 Apr 2018 18:08:39 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4D6AF21745 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=jhogan@kernel.org Date: Wed, 25 Apr 2018 23:08:34 +0100 From: James Hogan To: NeilBrown Cc: Ralf Baechle , Paul Burton , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MIPS: c-r4k: fix data corruption related to cache coherence. Message-ID: <20180425220834.GC25917@saruman> References: <87sh7klyhc.fsf@notabene.neil.brown.name> <20180425214650.GA25917@saruman> <87h8nzlzf1.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0lnxQi9hkpPO77W3" Content-Disposition: inline In-Reply-To: <87h8nzlzf1.fsf@notabene.neil.brown.name> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --0lnxQi9hkpPO77W3 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 26, 2018 at 08:00:18AM +1000, NeilBrown wrote: > On Wed, Apr 25 2018, James Hogan wrote: > > So I'm thinking "!mips_cm_present()" should probably be replaced with > > "!r4k_op_needs_ipi(R4K_INDEX)" (and the comment updated to mention that > > IPI calls aren't implemented here). >=20 > That makes sense. I tried ipi calls at one stage. Synchronous ones > cannot be used because this code is called with interrupts disabled, and > async ones cannot provide the required guarantees. Okay. I thought something like that might be the case. >=20 > I'll update the patch, test that it still works, and resend, in the next > day or so. Thanks. It wouldn't hurt to also mention why IPIs can't be used in the code comments, if its fresh in your mind, just for the benefit of next person to attempt it. Cheers James --0lnxQi9hkpPO77W3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iHUEARYIAB0WIQS7lRNBWUYtqfDOVL41zuSGKxAj8gUCWuD8YQAKCRA1zuSGKxAj 8qhiAQDy4PgqTJQrBqDyhppFRJRq1oCRGDz9EGtqFs51hCP9TgEArA/K9cg3Wszh ckssoKrrkL4uvnpylKDNzb9aP+4GAQM= =9Wdc -----END PGP SIGNATURE----- --0lnxQi9hkpPO77W3--