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_PASS,URIBL_BLOCKED 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 80C4FC10F05 for ; Fri, 29 Mar 2019 22:48:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 507202184D for ; Fri, 29 Mar 2019 22:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553899698; bh=NGweQ1I5s8Jq+objqslkHJmBFpAoDR+aQ5oCqiMIn7M=; h=In-Reply-To:References:From:Subject:Cc:To:Date:List-ID:From; b=ILPF7m6X9IN9UDisakJ9GqVT/4QRvplYr+CaK+cbiUFPtISWamhvRbx/X4Nl9Ljt7 bd/WMUf1xTF1Bq+AW0NigMn0THiiqOKaVe8Jqf2LQ/6WxqgJQ5fVFciEY1uy7dyOtA BgHyXpBa8Sx4/vFVXQGxFfkID8nhoXwB8nxKKGoY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730544AbfC2WsR (ORCPT ); Fri, 29 Mar 2019 18:48:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:54820 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730456AbfC2WsQ (ORCPT ); Fri, 29 Mar 2019 18:48:16 -0400 Received: from localhost (unknown [104.132.0.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 96FF0217F5; Fri, 29 Mar 2019 22:48:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553899695; bh=NGweQ1I5s8Jq+objqslkHJmBFpAoDR+aQ5oCqiMIn7M=; h=In-Reply-To:References:From:Subject:Cc:To:Date:From; b=fMlU3a7o0IYXKQmkQSOzYhjULpZDkTDT3JEwUwTWDf9mtnn2WkeYZn/Vu6WS7u56r T8FOXiC9u8J+Z0h5jyLT5Tf+jV4yeipjO78AUPNF641p+WVtjLlqA0Sr3HOjJKLj+3 Ukn/1O5o9bRnnpEMmUHbzIrYCOaV8QMYBGVfxdNI= Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: <1553859960-31501-1-git-send-email-nixiaoming@huawei.com> References: <1553859960-31501-1-git-send-email-nixiaoming@huawei.com> From: Stephen Boyd Subject: Re: [PATCH] clk:mmp: clk-mix.c fix divide-by-zero Cc: linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org To: chao.xie@marvell.com, mturquette@baylibre.com, nixiaoming@huawei.com Message-ID: <155389969479.20095.682832622477946593@swboyd.mtv.corp.google.com> User-Agent: alot/0.8 Date: Fri, 29 Mar 2019 15:48:14 -0700 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting nixiaoming (2019-03-29 04:46:00) > The _get_div function has a branch with a return value of 0 > Add a check on the return value of _get_div to avoid divide-by-zero >=20 > Signed-off-by: nixiaoming Similar questions apply here as they do on the generic divider patch you sent. > --- > drivers/clk/mmp/clk-mix.c | 4 ++++ > 1 file changed, 4 insertions(+) >=20 > diff --git a/drivers/clk/mmp/clk-mix.c b/drivers/clk/mmp/clk-mix.c > index 90814b2..9d152c2 100644 > --- a/drivers/clk/mmp/clk-mix.c > +++ b/drivers/clk/mmp/clk-mix.c > @@ -245,6 +245,8 @@ static int mmp_clk_mix_determine_rate(struct clk_hw *= hw, > div_val_max =3D _get_maxdiv(mix); > for (j =3D 0; j < div_val_max; j++) { > div =3D _get_div(mix, j); > + if (!div) /* avoid divide-by-zero */ Why can't we return 1 for the divider value here? > + continue; > mix_rate =3D parent_rate / div; > gap =3D abs(mix_rate - req->rate); > if (!parent_best || gap < gap_best) { > @@ -341,6 +343,8 @@ static unsigned long mmp_clk_mix_recalc_rate(struct c= lk_hw *hw, > shift =3D mix->reg_info.shift_div; > =20 > div =3D _get_div(mix, MMP_CLK_BITS_GET_VAL(mux_div, width, shift)= ); > + if (!div) /* avoid divide-by-zero */ Same question. > + return -EINVAL; > =20 > return parent_rate / div; > }