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Thu, 16 Jul 2020 22:03:15 +0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 06GM3CuA31851182 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Jul 2020 22:03:12 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 79F82C6062; Thu, 16 Jul 2020 22:03:14 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4DAC1C606C; Thu, 16 Jul 2020 22:03:11 +0000 (GMT) Received: from morokweng.localdomain (unknown [9.163.8.110]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTPS; Thu, 16 Jul 2020 22:03:10 +0000 (GMT) References: <159466074408.24747.10036072269371204890.stgit@hbathini.in.ibm.com> <159466091925.24747.6840028682768745598.stgit@hbathini.in.ibm.com> <87365s9ysj.fsf@morokweng.localdomain> User-agent: mu4e 1.2.0; emacs 26.3 From: Thiago Jung Bauermann To: Hari Bathini Subject: Re: [PATCH v3 06/12] ppc64/kexec_file: restrict memory usage of kdump kernel In-reply-to: Date: Thu, 16 Jul 2020 19:03:08 -0300 Message-ID: <875zance3n.fsf@morokweng.localdomain> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-16_11:2020-07-16, 2020-07-16 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_spam_definite policy=outbound score=100 phishscore=0 spamscore=100 priorityscore=1501 lowpriorityscore=0 suspectscore=0 impostorscore=0 mlxscore=100 bulkscore=0 adultscore=0 malwarescore=0 mlxlogscore=-1000 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007160142 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: , Cc: Pingfan Liu , Petr Tesarik , Nayna Jain , Kexec-ml , Mahesh J Salgaonkar , Mimi Zohar , lkml , linuxppc-dev , Sourabh Jain , Andrew Morton , Dave Young , Vivek Goyal , Eric Biederman Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hari Bathini writes: > On 16/07/20 4:22 am, Thiago Jung Bauermann wrote: >> >> Hari Bathini writes: >> > > > >>> +/** >>> + * get_node_path - Get the full path of the given node. >>> + * @dn: Node. >>> + * @path: Updated with the full path of the node. >>> + * >>> + * Returns nothing. >>> + */ >>> +static void get_node_path(struct device_node *dn, char *path) >>> +{ >>> + if (!dn) >>> + return; >>> + >>> + get_node_path(dn->parent, path); >> >> Is it ok to do recursion in the kernel? In this case I believe it's not >> problematic since the maximum call depth will be the maximum depth of a >> device tree node which shouldn't be too much. Also, there are no local >> variables in this function. But I thought it was worth mentioning. > > You are right. We are better off avoiding the recursion here. Will > change it to an iterative version instead. Ok. >>> + * each representing a memory range. >>> + */ >>> + ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells); >>> + >>> + for (i = 0; i < ranges; i++) { >>> + base = of_read_number(prop, n_mem_addr_cells); >>> + prop += n_mem_addr_cells; >>> + end = base + of_read_number(prop, n_mem_size_cells) - 1; > > prop is not used after the above. > >> You need to `prop += n_mem_size_cells` here. > > But yeah, adding it would make it look complete in some sense.. Isn't it used in the next iteration of the loop? -- Thiago Jung Bauermann IBM Linux Technology Center