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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39d995a42a5sm18760134a91.17.2026.09.13.23.25.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Sep 2026 23:25:38 -0700 (PDT) Message-ID: <7c6b728a-38e8-41d0-b99e-85a09a79a0b1@oss.qualcomm.com> Date: Mon, 14 Sep 2026 14:25:34 +0800 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: Gavin Shan , Andre Przywara , James Morse , Ben Horgan Cc: Reinette Chatre , Fenghua Yu , Tony Luck , Dave Martin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260902143757.3469690-1-andre.przywara@arm.com> <095ebf41-e3c1-4e7e-b6f9-84b6f94da3ce@redhat.com> Content-Language: en-US From: Yin Li In-Reply-To: <095ebf41-e3c1-4e7e-b6f9-84b6f94da3ce@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Authority-Analysis: v=2.4 cv=RY0FmFtv c=1 sm=1 tr=0 ts=6aa79364 cx=c_pps a=0uOsjrqzRL749jD1oC5vDA==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_K5XuSEh1TEqbUxoQ0s3:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=7CQSdrXTAAAA:8 a=20KFwNOVAAAA:8 a=TdcjmqNvtQ7Mihavh1wA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=mQ_c8vxmzFEMiUWkPHU9:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE0MDA4OSBTYWx0ZWRfX2quRbLdvhjcJ D/agZFMakDm/XCaNJx5qVUIz1q1L+3sK0QX4GmTu+l+uI8gJdk0Hroi8jJ2GY6vFIusht0O0B59 GYhnZmVvvoHNwEJAQnHSV017imatb64EuHL6cz1gULt74ntA/awIRr8DyGzUo+cdkcKf+8cAPKq yuJ/PvNpRJiRYRSM+PLuH36cTQimNS/azzzl/u2NWHvDW45R7ANTAdU/zaM1vd2kVe/FXdk/aG0 Zu1pd0bhp650zCmZO4Rrv0muId1S5lk2qrSsyviPh7gk/bOPOZ10dmsfmi+D46e0G8TsRVMekiw U58gcAMsaAOUrYN7QBU1oPY4a9aRMlelZ3fYaNIcay7R4A+OdQvncSDM7vcnd3P2itwtYpd3srQ S7zvzaUuhf7c0w89qpEYXztBFzi9X3FdQpTGN/6n0fHBX3W26EvbxDJr/YwGVHdBSrBtfMBKCy4 DmN2NPnjQJhl8kpp4dQ== X-Proofpoint-ORIG-GUID: 0_7wFVx7SYIz6e91vwDm2-MBxgcxJ0Ib X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE0MDA4OSBTYWx0ZWRfX4ld6XvLlPhhS Rd4cAMseEcRxr7MM4byXyqiKJKNiUGbZlaIi3LWJVYSwijro28mMkBn5hX0/XbIkxEwJQyT7kdO 6NlynWK8YhDqz41VeWbP2t2lzE3K9bU= X-Proofpoint-GUID: 0_7wFVx7SYIz6e91vwDm2-MBxgcxJ0Ib X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-14_02,2026-09-13_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 spamscore=0 suspectscore=0 lowpriorityscore=0 impostorscore=0 phishscore=0 malwarescore=0 bulkscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609140089 On 9/14/2026 2:14 PM, Gavin Shan wrote: > On 9/3/26 12:37 AM, 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 >> --- >>   drivers/resctrl/mpam_resctrl.c | 5 ++++- >>   1 file changed, 4 insertions(+), 1 deletion(-) >> > > Reviewed-by: Gavin Shan > >> 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(); > > find_l3_equivalent_bitmask() passes @cache_id to > find_l3_equivalent_bitmask() as > a 'unsigned long' argument. Actually, it can be 'u32'. It's not directly > related > to this patch though. > > int mpam_get_cpumask_from_cache_id(unsigned long cache_id, ...); > > can be: > > int mpam_get_cpumask_from_cache_id(u32 cache_id, ...); > Hi Gavin, Thanks for pointing this out. I've made exactly this change in my MPAM DT series (v2, in preparation) — mpam_get_cpumask_from_cache_id() is changed from unsigned long to u32 there, along with the related cache-id variables. https://lore.kernel.org/all/20260811-mpam-resctrl-dt-knp-support-v1-6-ea6397bead59@oss.qualcomm.com/ I'm about to post v2 of that series and will make sure you're on Cc, in case you'd like to take a look. Thanks, Yin > Thanks, > Gavin > -- Thx and BRs, Yin