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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D645C433FE for ; Mon, 10 Jan 2022 17:29:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238319AbiAJR3E (ORCPT ); Mon, 10 Jan 2022 12:29:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238284AbiAJR3C (ORCPT ); Mon, 10 Jan 2022 12:29:02 -0500 Received: from mail-ot1-x329.google.com (mail-ot1-x329.google.com [IPv6:2607:f8b0:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 94EC5C06173F; Mon, 10 Jan 2022 09:29:02 -0800 (PST) Received: by mail-ot1-x329.google.com with SMTP id j6-20020a056830240600b00590eab8f4fbso1156570ots.8; Mon, 10 Jan 2022 09:29:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=7gfWYRvC8m3v/szxt6rnVGDFWH+WIQ1HB5K0b5pwINM=; b=PPbPIV/LeGYUdXkEAmODbYLTtpunWWhlhV4mRxBUZc4DOhsVqf+WkV+Cerlq9W+0PK 2tpXw89IQRkDtSSkermTUYFj1KV8Hd9G3O5ilhprVGGXvOz72CTuzEuRB6NYD7WBBnKo 1IiGIcM8oZP2membzetBEazFn1ujtE1wzclac+zz+QAa4g+FEQo2GqCjEI3vSHAq9x4c SU3B5eNvY5sBTe/COw2te9GGET52cSBtruU5fBaxrlPB5m//iLgR5G/tP4O2O0FgGCTI sjM0y2sWT9+u1d9WSNDh7KC/iabkn1NkfR4aDJX3k2LBec2lpTTD04SDIjDsZvfB1QRg LI1g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=7gfWYRvC8m3v/szxt6rnVGDFWH+WIQ1HB5K0b5pwINM=; b=2Ejo+8o9abXZ2/OWJDhVXjYU23ZUOFmfXNrvJO48LVNpIYP7Lnsr58csPmHjfSbzNq eUMvFX6lSFEkPanUvQVgc6hvKb9NZNP6x8U6pCuvYvgumh8Z46/BeWM6FKov0ami/KOD Iow8H7HI2H3DfloKmiBYddAEdF0BDALQHrhBQIb2ySBM4lSp4RZr21t6sIw41fuQsp0q ieo3Ke5KCjsI5dynLzJ91XRhtZS/qB0cyg3waVa7ZSvlOdLqSKXapz3EueqrIsI+MRrb MELBXkmeUDmnAFeMl6X+5gCBdlF5cZUHA4RSd1UZhC3ccj1XjEVUrjC4zezRvhjLL8dS BGAw== X-Gm-Message-State: AOAM53251rsfHtkO06m/IpKrCmx3LAhQJfTYV7qaONqcfA5rZoO9uiwC b+zVqMjk3Bk/iNmqHL69AiH1nySjkj0= X-Google-Smtp-Source: ABdhPJwMyf6Ml71veWa0UvqQDnZpN3v/oN9/brCsvv4Js2K3lIt6cboh47xY6ofJywyTJDujTESNwQ== X-Received: by 2002:a9d:bf7:: with SMTP id 110mr634464oth.94.1641835741910; Mon, 10 Jan 2022 09:29:01 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id v7sm1237158oiv.46.2022.01.10.09.29.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Jan 2022 09:29:01 -0800 (PST) Sender: Guenter Roeck From: Guenter Roeck To: Wolfram Sang Cc: Jean Delvare , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Guenter Roeck Subject: [PATCH 0/2] i2c: smbus: Handle stuck alerts Date: Mon, 10 Jan 2022 09:28:55 -0800 Message-Id: <20220110172857.2980523-1-linux@roeck-us.net> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While playing with SMBus alert functionality, I noticed the following messages if alert was active on more than once device. smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0 smbus_alert 3-000c: no driver alert()! or: smbus_alert 3-000c: SMBALERT# from dev 0x28, flag 0 This is seen if multiple devices assert alert at the same time and at least one of them does not or not correctly implement SMBus arbitration. Once it starts, this message repeats forever at high rate. Worst case, the problem turn resulted in system crashes after a while. The following two patches fix the problem for me. The first patch aborts the endless loop in smbus_alert() if no handler is found for an alert address. The second patch sends alerts to all devices with alert handler if that situation is observed. I split the changes into two patches since I figured that the first patch might be easier to accept. However, both patches are really needed to fix the problem for good. Note that there is one situation which is not addressed by this set of patches: If the corrupted address points to yet another device with alert handler on the same bus, the alert handler of that device will be called. If it is not a source of the alert, we are back to the original problem. I do not know how to address this case. ---------------------------------------------------------------- Guenter Roeck (2): i2c: smbus: Improve handling of stuck alerts i2c: smbus: Send alert notifications to all devices if source not found drivers/i2c/i2c-smbus.c | 64 ++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 58 insertions(+), 6 deletions(-)