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[85.228.174.190]) by smtp.gmail.com with ESMTPSA id f22sm7456128ljn.66.2020.06.29.06.06.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2020 06:06:45 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1jptUi-0007Vk-Lx; Mon, 29 Jun 2020 15:06:45 +0200 Date: Mon, 29 Jun 2020 15:06:44 +0200 From: Johan Hovold To: Lee Jones Subject: Re: [PATCH 4/5] mfd: sprd-sc27xx-spi: Fix divide by zero when allocating register offset/mask Message-ID: <20200629130644.GU3334@localhost> References: <20200629123215.1014747-1-lee.jones@linaro.org> <20200629123215.1014747-5-lee.jones@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200629123215.1014747-5-lee.jones@linaro.org> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Baolin Wang , Orson Zhai , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Chunyan Zhang Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 29, 2020 at 01:32:14PM +0100, Lee Jones wrote: > Since ddata->irqs[] is already zeroed when allocated by devm_kcalloc() and > dividing 0 by anything is still 0, there is no need to re-assign > ddata->irqs[i].* values. Instead, it should be safe to begin at 1. > > This fixes the following W=1 warning: > > drivers/mfd/sprd-sc27xx-spi.c:255 sprd_pmic_probe() debug: sval_binop_unsigned: divide by zero > > Cc: Orson Zhai > Cc: Baolin Wang > Cc: Chunyan Zhang > Signed-off-by: Lee Jones > --- > drivers/mfd/sprd-sc27xx-spi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mfd/sprd-sc27xx-spi.c b/drivers/mfd/sprd-sc27xx-spi.c > index c305e941e435c..694a7d429ccff 100644 > --- a/drivers/mfd/sprd-sc27xx-spi.c > +++ b/drivers/mfd/sprd-sc27xx-spi.c > @@ -251,7 +251,7 @@ static int sprd_pmic_probe(struct spi_device *spi) > return -ENOMEM; > > ddata->irq_chip.irqs = ddata->irqs; > - for (i = 0; i < pdata->num_irqs; i++) { > + for (i = 1; i < pdata->num_irqs; i++) { > ddata->irqs[i].reg_offset = i / pdata->num_irqs; > ddata->irqs[i].mask = BIT(i % pdata->num_irqs); > } This doesn't look right either. First, the loop is never executed if num_irqs is zero. Second, the current code looks bogus too as reg_offset is always set to zero and mask to BIT(i)... Johan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9E21BC433E1 for ; Mon, 29 Jun 2020 21:17:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72FD1206A1 for ; Mon, 29 Jun 2020 21:17:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593465464; bh=2VjGLijjtJnODGSkJ1SgcA2IUwDBP0kg9dkApMQuTMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=MznpqryNu9ip+KXfA3ttZpr+cPWvYDNolRt7w8pMchce5mLLgvHfgohjioQp8rUX7 VL+QyJowtnEarZBsnzrWxoEpdtzV8PSVTiHIzNbjTlby43BuSItNGt876RWTBptTJ+ 8EhFBOYjzw+9YdtbVQQhznZeXFhqSxM7zURw58no= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390760AbgF2VRn (ORCPT ); Mon, 29 Jun 2020 17:17:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729801AbgF2Swv (ORCPT ); Mon, 29 Jun 2020 14:52:51 -0400 Received: from mail-lj1-x242.google.com (mail-lj1-x242.google.com [IPv6:2a00:1450:4864:20::242]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A625DC02A556 for ; Mon, 29 Jun 2020 06:06:47 -0700 (PDT) Received: by mail-lj1-x242.google.com with SMTP id q7so4699983ljm.1 for ; Mon, 29 Jun 2020 06:06:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=YWzRxTXrUasbGXUFwSr2i2nPcUT+2MUUycvRS8lYyrM=; b=hqb37tRcYrufOBW+bXtELSQb8eYyvV7u0oFo6Bx5fAjCfViqRn2BQVIz2frQYJdkXB gXpzQ5MoWm0Cu3sX93zhH3N79e3A3T0Htjl3gfeybeV0vGV0SWiy4c4HY2OIF5jIfSII CHaWmMFuJ1TDwImjAOscqtMLSVzUGDaIHDRDzKpofeu64bwHeZcxFo66gfPEFMTQzNCf 1L/EZ0Uocdy4G2ludZCWovpgryyPQgRY1qUPLbk5iJXVkHMk98wg8Ul8TdMjMr/8oNVO Hcbl2h5puCqxc3+MftLIHIkeIs44shq1RMsHbycGOXbBsg+aXArbwiordsyLNyNi26+n +2NA== X-Gm-Message-State: AOAM5339x94fU/prGU2zQFcGqf7c6tM1Yb4Z6nzxiwzoBaDP0alBL2Vz MilQXJlZa74jOv9hBMv4BOs= X-Google-Smtp-Source: ABdhPJwQFKL4/TMXmQS8Je9ya6myBWYfn8LiUhyH3xk8GCLpw4qDQMLOc/6BbQ7ZvG4DSGtm/UrBtQ== X-Received: by 2002:a2e:b55a:: with SMTP id a26mr3583999ljn.349.1593436005924; Mon, 29 Jun 2020 06:06:45 -0700 (PDT) Received: from xi.terra (c-beaee455.07-184-6d6c6d4.bbcust.telenor.se. [85.228.174.190]) by smtp.gmail.com with ESMTPSA id f22sm7456128ljn.66.2020.06.29.06.06.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2020 06:06:45 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.93.0.4) (envelope-from ) id 1jptUi-0007Vk-Lx; Mon, 29 Jun 2020 15:06:45 +0200 Date: Mon, 29 Jun 2020 15:06:44 +0200 From: Johan Hovold To: Lee Jones Cc: Baolin Wang , Orson Zhai , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Chunyan Zhang Subject: Re: [PATCH 4/5] mfd: sprd-sc27xx-spi: Fix divide by zero when allocating register offset/mask Message-ID: <20200629130644.GU3334@localhost> References: <20200629123215.1014747-1-lee.jones@linaro.org> <20200629123215.1014747-5-lee.jones@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200629123215.1014747-5-lee.jones@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 29, 2020 at 01:32:14PM +0100, Lee Jones wrote: > Since ddata->irqs[] is already zeroed when allocated by devm_kcalloc() and > dividing 0 by anything is still 0, there is no need to re-assign > ddata->irqs[i].* values. Instead, it should be safe to begin at 1. > > This fixes the following W=1 warning: > > drivers/mfd/sprd-sc27xx-spi.c:255 sprd_pmic_probe() debug: sval_binop_unsigned: divide by zero > > Cc: Orson Zhai > Cc: Baolin Wang > Cc: Chunyan Zhang > Signed-off-by: Lee Jones > --- > drivers/mfd/sprd-sc27xx-spi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mfd/sprd-sc27xx-spi.c b/drivers/mfd/sprd-sc27xx-spi.c > index c305e941e435c..694a7d429ccff 100644 > --- a/drivers/mfd/sprd-sc27xx-spi.c > +++ b/drivers/mfd/sprd-sc27xx-spi.c > @@ -251,7 +251,7 @@ static int sprd_pmic_probe(struct spi_device *spi) > return -ENOMEM; > > ddata->irq_chip.irqs = ddata->irqs; > - for (i = 0; i < pdata->num_irqs; i++) { > + for (i = 1; i < pdata->num_irqs; i++) { > ddata->irqs[i].reg_offset = i / pdata->num_irqs; > ddata->irqs[i].mask = BIT(i % pdata->num_irqs); > } This doesn't look right either. First, the loop is never executed if num_irqs is zero. Second, the current code looks bogus too as reg_offset is always set to zero and mask to BIT(i)... Johan