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 E16BFC79F89 for ; Mon, 7 Sep 2026 13:14:20 +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=PwQdpGO5V3CPOgrnb2NRsGwjwQZWnzlGvHbQpClskgY=; b=12KlXakWDbEftzzMOVmvM0ZQOm os8UG1A+xxtp7GbtusH+2/QPdv/VWzgQLp6LQYHioM6NoPptTiSqISo5S4y9J3BfFumOCCZeadAYf fIaLpuSmbtzjH+RWJXliiCY6MuuEcA8HGbzQULrK1CAuCHtb/xu8a8rJ+Kn1tASkvdDvAguPjYLWp eXDS8AQkoh35chg/H3rwAjjUce0ca0yga7WYB99lYGuX9DZ7a+bsNmEv9jfjSGGoxPQUveYlUfP1Q LbCjYmB0JU6sb//fZ5FVShthqdF72tigBR1J6pHjmi05/vI4ctGygpWs2sEaY0Ox/LzMPRVNgW1Ud +oQPPAow==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3ZAr-00000006uNB-2rOm; Mon, 07 Sep 2026 13:14:13 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x3ZAq-00000006uMZ-00p2 for linux-arm-kernel@lists.infradead.org; Mon, 07 Sep 2026 13:14:13 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 08C841476; Mon, 7 Sep 2026 06:14:05 -0700 (PDT) Received: from [10.57.7.12] (unknown [10.57.7.12]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4818F3F7D8; Mon, 7 Sep 2026 06:14:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788786848; bh=XWLt2OmFnj478hxlI5SLGUXw2C8SjtcuYR3m957GDEI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=DlIReHo4IXFAsHTh3mJ60nbj3okusPpJbvnauJK1CVeqYxdGOUmmuK3cOSzJsIJ+g JWMitI4SSa4Cph7NPhgFStdu3qr3E1rg4bg1AweLFBfEvTJ+IfjrcZYlVKsqgol1Zx HRqnqGsUEu7yqoUCUgbhZsitwnWZSzdz7tvB72d8= Message-ID: <99baf0a9-e9e8-49c5-a550-78c10a3ef702@arm.com> Date: Mon, 7 Sep 2026 15:14:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm_mpam: resctrl: Catch and propagate error from get_cpu_cacheinfo_id() To: Ben Horgan , James Morse Cc: Reinette Chatre , Fenghua Yu , Tony Luck , Dave Martin , Yin Li , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260902143757.3469690-1-andre.przywara@arm.com> Content-Language: en-GB From: Andre Przywara In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260907_061412_092341_4056A326 X-CRM114-Status: GOOD ( 17.93 ) 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 Hi Ben, thanks for having a look! On 9/7/26 14:59, Ben Horgan wrote: > Hi Andre, > > On 02/09/2026 15:37, Andre Przywara wrote: >> get_cpu_cacheinfo_id() can fail, in which case it returns a negative >> error value. >> >> Check the returned value for this error condition, before passing the >> value on to other code, which would hide the negative number in some high >> value in the unsigned type. >> >> Fixes: 36528c7681b8 ("arm_mpam: resctrl: Add support for 'MB' resource") >> Signed-off-by: Andre Przywara > > This looks good to me. Out of interest what led you to find this? For Yin Li's RFC patch [06/15], I was looking around to find the proper type for cache-id, and stumbled upon this. > Reviewed-by: Ben Horgan Thanks! Cheers, Andre > > Thanks, > > Ben > >> --- >> drivers/resctrl/mpam_resctrl.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c >> index 9d223057953ab..a5e661eff86d7 100644 >> --- a/drivers/resctrl/mpam_resctrl.c >> +++ b/drivers/resctrl/mpam_resctrl.c >> @@ -786,7 +786,10 @@ static u32 get_mba_min(struct mpam_props *cprops) >> /* Find the L3 cache that has affinity with this CPU */ >> static int find_l3_equivalent_bitmask(int cpu, cpumask_var_t tmp_cpumask) >> { >> - u32 cache_id = get_cpu_cacheinfo_id(cpu, 3); >> + int cache_id = get_cpu_cacheinfo_id(cpu, 3); >> + >> + if (cache_id < 0) >> + return -ENOENT; >> >> lockdep_assert_cpus_held(); >> >