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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, 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 CE0D6C433F1 for ; Mon, 27 Jul 2020 04:32:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A57B420714 for ; Mon, 27 Jul 2020 04:32:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="D8HCNvbb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbgG0Ec2 (ORCPT ); Mon, 27 Jul 2020 00:32:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726541AbgG0EcX (ORCPT ); Mon, 27 Jul 2020 00:32:23 -0400 Received: from mail-lf1-x142.google.com (mail-lf1-x142.google.com [IPv6:2a00:1450:4864:20::142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD4D2C0619D4 for ; Sun, 26 Jul 2020 21:32:22 -0700 (PDT) Received: by mail-lf1-x142.google.com with SMTP id m15so7572772lfp.7 for ; Sun, 26 Jul 2020 21:32:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=y2MT8K7LJP0h4HIjUSHIF3kx72ZyLwnnER3/s7uorqE=; b=D8HCNvbbfeCXTArUC4WY1QDrs9HjLspd9XS6l+ZIduQcykgLo9mIag8AEPoxijQdxx N0I6GZ6ggif98PyvczFJQTezcR085wLtKWpW32z+fnl1YcUMRliE2ieD4PCcJ+Af9qM5 XgNj7w46y1O7ff2pkN657Rpag5lZjbuv52oqk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=y2MT8K7LJP0h4HIjUSHIF3kx72ZyLwnnER3/s7uorqE=; b=M8Kl3aTyNyi0mlLxLZd6rHlxgqgy9CZfXhp5KX0olqHVrDs65Ai6enlvDmVpQVWz6L pjNsPpCtpPLLY+eQ6U73I2Ka6pO8MDkzW+dQNLvg8dVzcnTk0/znbtQFYszl/QFX9+zW Y9AVgPMd+GZ1CcA045jbObWprvKosYXapMJlRLxfidLUB3f3lMsf+2qxs4Zp5oACRWhw HqcrTZqRayAuSaatrEDY1qEZBsenelHpRxPQWr7NENYg87CY97SrfzCxmU8PRhYeJKK4 TVbE7kD6CHnld4kHBBVRa69E+E+UfRFuF+Afuy/5jTGDXmOfi4RkFNj3fia5W40Kke5y heMw== X-Gm-Message-State: AOAM530kUm0Qp88NVcYCI38HySwS9wxwodKhAaN0aJBHugYxwsR8Mie9 siQUQ4Q6wmgpEsKtcVyuQYFq/8LZLG5RfStbL6iWzA== X-Google-Smtp-Source: ABdhPJyPqCU/OdRwDZPqwlMkGbnhgQCLKdZNaMgRtj9kGkbaFfHHszQybGc/isZ4yrfqqymo2EzDGJjUEh54mtwmKWg= X-Received: by 2002:ac2:5502:: with SMTP id j2mr9290650lfk.50.1595824340928; Sun, 26 Jul 2020 21:32:20 -0700 (PDT) MIME-Version: 1.0 References: <1595115599-100054-1-git-send-email-dphadke@linux.microsoft.com> <116ac90c-8b49-ca89-90a4-9a28f43a7c50@broadcom.com> <20200722104128.GK1030@ninjato> <5048cf44-e2c2-ee31-a9fb-b823f16c2c7d@broadcom.com> <20200725101815.GA1519@ninjato> In-Reply-To: <20200725101815.GA1519@ninjato> From: Rayagonda Kokatanur Date: Mon, 27 Jul 2020 10:02:09 +0530 Message-ID: Subject: Re: [PATCH] i2c: iproc: fix race between client unreg and isr To: Wolfram Sang Cc: Ray Jui , Dhananjay Phadke , linux-i2c , Linux Kernel Mailing List , Ray Jui , BCM Kernel Feedback Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 25, 2020 at 3:48 PM Wolfram Sang wrote: > > > > I think the following sequence needs to be implemented to make this > > safe, i.e., after 'synchronize_irq', no further slave interrupt will be > > fired. > > > > In 'bcm_iproc_i2c_unreg_slave': > > > > 1. Set an atomic variable 'unreg_slave' (I'm bad in names so please come > > up with a better name than this) > > > > 2. Disable all slave interrupts > > > > 3. synchronize_irq > > > > 4. Set slave to NULL > > > > 5. Erase slave addresses > > What about this in unreg_slave? > > 1. disable_irq() > This includes synchronize_irq() and avoids the race. Because irq > will be masked at interrupt controller level, interrupts coming > in at the I2C IP core level should still be pending once we > reenable the irq. > > 2. disable all slave interrupts > > 3. enable_irq() > > 4. clean up the rest (pointer, address) > > Or am I overlooking something? This sequence will take care of all cases. @Dhananjay Phadke is it possible to verify this from your side once. Best regards, Raaygonda