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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9F73FC8303F for ; Thu, 28 Aug 2025 17:26:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=P7v68eUbMhdBb1FN26U9K+vJv5tGLAeNVJMhgqgmwlM=; b=xSFLZsXLuADrld1/HPkRubdL1j 5/NqzwEMwpGRP/96ZuE5qePKBK9cPT/ZLeGwgEYk1QQmaeWJeeAXaeOYj+1OhSwaekP1iVNbvjQ6t nhu1RP5uMmfHbWWVUiPbnlhhQz9vzzjLm0QLZxpg16t8JUBxzuX/vXxERESdyuZRk1BMhIPOCTJhK vy6Zo0tKGH2WxOLo+oFsE0KrZVUSM507FUDrY1tttOPEEz5p1JV/FeO0bzmdgFyx2rKaj6wGUSN38 fxPL3MZiI+aS7Ukw7VR9T/PeHUB46y3htCNd4VfsFjhrOXS0CbiY54846w1Hc85UZa7F3s9qRZVZ8 yIKwfb9A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1urgNz-00000002SsP-30gV; Thu, 28 Aug 2025 17:26:07 +0000 Received: from out-188.mta0.migadu.com ([2001:41d0:1004:224b::bc]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1urcG4-00000001esu-08fx for linux-arm-kernel@lists.infradead.org; Thu, 28 Aug 2025 13:01:41 +0000 Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756386087; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=P7v68eUbMhdBb1FN26U9K+vJv5tGLAeNVJMhgqgmwlM=; b=ra8FPJf02ezT/Z6Od+0hGN4l4CJBp5cRRQwc7kivX348XlYc76qHJiTCY2Zbr6BzuhziWV vtp6ovLknz+EW3nWC8g/Y5koIGMS61GWL+j18xx61d5DIBaIiGVrOdIF2zednYc5wZw2gS Hu5qlNzC2MneYgUfwtN/+OFL0BuZwcQ= Date: Thu, 28 Aug 2025 14:01:23 +0100 MIME-Version: 1.0 Subject: Re: [PATCH] net: ethernet: ti: Prevent divide-by-zero in cpts_calc_mult_shift() To: =?UTF-8?B?5p6X5aaZ5YCp?= Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , Thomas Gleixner , Grygorii Strashko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org References: <20250828092224.46761-1-linmq006@gmail.com> <11d46e56-b8d9-4776-9969-d3767d8cda41@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Vadim Fedorenko In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250828_060140_204469_064D68CC X-CRM114-Status: GOOD ( 11.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 28/08/2025 13:38, æå¦å© wrote: > Hi, Vadim > > Vadim Fedorenko 于2025年8月28日周四 20:06写道： >> >> On 28/08/2025 10:22, Miaoqian Lin wrote: >>> cpts_calc_mult_shift() has a potential divide-by-zero in this line: >>> >>> do_div(maxsec, freq); >>> >>> due to the fact that clk_get_rate() can return zero in certain error >>> conditions. >> >> Have you seen this happening in the real environment, or is it just >> analysis of the code? I don't see a reason for these "certain error >> conditions" to happen... > > This is from code analysis, not from real environment. > The !CONFIG_HAVE_CLK version of clk_get_rate() returns zero. > With CONFIG_COMPILE_TEST && !CONFIG_HAVE_CLK could have the problem. > This may be theoretical. !CONFIG_HAVE_CLK will have cpts_create() doing nothing as defined in cpts.h and it means the patch fixes impossible scenario. NAck