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Thu, 16 Jul 2020 21:10:07 +0000 (GMT) Received: from [9.102.2.181] (unknown [9.102.2.181]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 16 Jul 2020 21:10:07 +0000 (GMT) From: Hari Bathini Subject: Re: [PATCH v3 06/12] ppc64/kexec_file: restrict memory usage of kdump kernel To: Thiago Jung Bauermann References: <159466074408.24747.10036072269371204890.stgit@hbathini.in.ibm.com> <159466091925.24747.6840028682768745598.stgit@hbathini.in.ibm.com> <87365s9ysj.fsf@morokweng.localdomain> Message-ID: Date: Fri, 17 Jul 2020 02:40:06 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <87365s9ysj.fsf@morokweng.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 malwarescore=0 priorityscore=1501 adultscore=0 clxscore=1015 bulkscore=0 spamscore=100 suspectscore=0 impostorscore=0 mlxlogscore=-1000 lowpriorityscore=0 mlxscore=100 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007160140 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" 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. >> + * 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.. Thanks Hari