From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C593F47FAEA for ; Mon, 7 Sep 2026 12:59:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788785973; cv=none; b=G1JHsnvmxla5a5oG096n95H9EuwCvTZcj1M6TCIbUL9QGn89HIJN7Tp/TNYLKAnob5MDg+Uhji/0ONwOCeFGnxK5kMvqP9la+W/KFKiamULLk22T9XW9DHv+BWKE5ew/CcAVOh2FX+dLFY0ZR4H7Lmgab3t9LLQGDayGViP96wE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788785973; c=relaxed/simple; bh=fs6D9307+D5ofEdJVbGr/fE9RQA62x0tlXgWzmyLjRc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=VksWGTkueX2n3WxbS69y3gCALFNfjUfOvnEGRkyCejspKTCXQgWtMBkim9rBjVfb8r0M/lvwu8yiFPqQTxO2mxtReMzV1s0078Xuq4pArkMTmq8pziCRtqOrLq99kYJC/j1u9CzseY1hA8scEWvVt5TQOFGayrjGRqdJeqHtwiI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=u233w6RG; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="u233w6RG" 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 7758D1476; Mon, 7 Sep 2026 05:59:13 -0700 (PDT) Received: from [10.2.212.8] (e134344.arm.com [10.2.212.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D4F033F7D8; Mon, 7 Sep 2026 05:59:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788785957; bh=fs6D9307+D5ofEdJVbGr/fE9RQA62x0tlXgWzmyLjRc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=u233w6RGdA63wnnNOM1ASAwHeUBU9au3b10Ya20EViUQr9/u/7lzCA0HCjc7gpO6l NEj+i2bTMvaL5FGzTDGLjpvKlyE8gThWSFwbZdk8fIdt0fARLgl6r4RJnSkSzPa/ai WUpyFueqgRTQ4D5MDkaI/ABLRrSN3tYBa86tkZXM= Message-ID: Date: Mon, 7 Sep 2026 13:59:14 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm_mpam: resctrl: Catch and propagate error from get_cpu_cacheinfo_id() To: Andre Przywara , 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-US From: Ben Horgan In-Reply-To: <20260902143757.3469690-1-andre.przywara@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit 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? Reviewed-by: Ben Horgan 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(); >