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Wed, 29 Jul 2020 16:03:46 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3E0E042045; Wed, 29 Jul 2020 16:03:45 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av24.portsmouth.uk.ibm.com (Postfix) with SMTP; Wed, 29 Jul 2020 16:03:45 +0000 (GMT) Date: Wed, 29 Jul 2020 21:33:44 +0530 From: Srikar Dronamraju To: Sandipan Das Subject: Re: [PATCH v2] selftests: powerpc: Fix online CPU selection Message-ID: <20200729160344.GB14603@linux.vnet.ibm.com> References: <20200609073733.997643-1-sandipan@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20200609073733.997643-1-sandipan@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-29_10:2020-07-29, 2020-07-29 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 suspectscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 bulkscore=0 spamscore=0 clxscore=1015 mlxlogscore=999 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007290108 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Srikar Dronamraju Cc: kamalesh@linux.vnet.ibm.com, shiganta@in.ibm.com, nasastry@in.ibm.com, harish@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" * Sandipan Das [2020-06-09 13:07:33]: > The size of the CPU affinity mask must be large enough for > systems with a very large number of CPUs. Otherwise, tests > which try to determine the first online CPU by calling > sched_getaffinity() will fail. This makes sure that the size > of the allocated affinity mask is dependent on the number of > CPUs as reported by get_nprocs(). > > Fixes: 3752e453f6ba ("selftests/powerpc: Add tests of PMU EBBs") > Reported-by: Shirisha Ganta > Signed-off-by: Sandipan Das > Reviewed-by: Kamalesh Babulal > --- > Previous versions can be found at: > v1: https://lore.kernel.org/linuxppc-dev/20200608144212.985144-1-sandipan@linux.ibm.com/ > > @@ -88,28 +89,40 @@ void *get_auxv_entry(int type) > > int pick_online_cpu(void) > { > - cpu_set_t mask; > - int cpu; > + int ncpus, cpu = -1; > + cpu_set_t *mask; > + size_t size; > + > + ncpus = get_nprocs(); Please use get_nprocs_conf or sysconf(_SC_NPROCESSORS_CONF). The manpage seems to suggest the latter. Not sure how accurate the manpage is. get_nprocs is returning online cpus and when smt is off, the cpu numbers would be sparse and hence the result from get_nprocs wouldn't be ideal for allocating cpumask. However get_nprocs_conf would return the max configured cpus and would be able to handle it. I think this was the same situation hit by Michael Ellerman. > + size = CPU_ALLOC_SIZE(ncpus); > + mask = CPU_ALLOC(ncpus); > + if (!mask) { > + perror("malloc"); > + return -1; > + } > -- Thanks and Regards Srikar Dronamraju