From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934009AbdKBQDv (ORCPT ); Thu, 2 Nov 2017 12:03:51 -0400 Received: from mail-by2nam03on0075.outbound.protection.outlook.com ([104.47.42.75]:52843 "EHLO NAM03-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933921AbdKBQDq (ORCPT ); Thu, 2 Nov 2017 12:03:46 -0400 Subject: Re: [PATCH 3/7] MIPS: Octeon: Add a global resource manager. To: Andrew Lunn , David Daney Cc: linux-mips@linux-mips.org, ralf@linux-mips.org, James Hogan , netdev@vger.kernel.org, "David S. Miller" , Rob Herring , Mark Rutland , linux-kernel@vger.kernel.org, "Steven J. Hill" , devicetree@vger.kernel.org, Carlos Munoz References: <20171102003606.19913-1-david.daney@cavium.com> <20171102003606.19913-4-david.daney@cavium.com> <20171102122327.GE4772@lunn.ch> From: David Daney Message-ID: Date: Thu, 2 Nov 2017 09:03:42 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171102122327.GE4772@lunn.ch> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [50.233.148.156] X-ClientProxiedBy: DM5PR07CA0043.namprd07.prod.outlook.com (10.168.109.29) To DM5PR07MB3498.namprd07.prod.outlook.com (10.164.153.29) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 13537de9-0e37-4ee4-89fa-08d5220b4ba5 X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(4534020)(4602075)(4627115)(201703031133081)(201702281549075)(2017052603238);SRVR:DM5PR07MB3498; X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB3498;3:F23d+XpKO37/PQGGaVTn9XByh3K/5oHr4aQS0iQCXMhhXyaCh5E+ggao2oTmZC2KkP8dEAOcQJYeKCO9+H8Or8izU5Wo7JMorw00TWXtZuQdqMUXNXL/WJKahrRcgyO5OWEMCLJfTNta3MT/04Vdrcm1iImqY3aY9H72kzxMB2IaVT4+T8KYbGrzRpNNYAk8Cvde3jmtS4GTwNGex/W+6o3yKR3Wsnb+elA1s3SmycJ+s11uYlDam3JVTYxq1aBj;25:QKGmt2GO4OvwYSX74iUocfOpANIDEU2380GZbx4deb7Be9Nd1esqObiVFLlkOIobRwrAUdsMWOGHK9qOkCCSYo1xQVjnXHsFDr+84LFTJN+rdy8irQRjvQ0Hll9lR6wcf3yj6Hre3CzApE3vXeX6nXDKGr/pDFl2VqMrqlOStqA55/wYz0T4jG+oC16oqmPGF2dK9liz12fqrFuKG4pRVP3aeDJNuaHb1frNr4YJdFeDsQum6Q7s1Bw+A7XlE/hl4oW53pRb4BvB3RfMpF6KhVFlotFR5VkJAeyfxJ4QRZ6hovUwu+Ocf6YZ4/glYIJQ3iG9I0yAcizUyLWiu7e3Ig==;31:yP5n6HfxT6e0YBBSLvWzlJlSF8iBE3lOBjxCNRrQQOzuXSbMViXHyDLvZXVAqeTHTOO1tHMHLHRLvdGe4ateVku7i0rl3myMcRK1YPU5C/tuDh0e8Mxj9R2iteV1YaFxdMOfV+ntIL9Gr0jrAeGfymnbQQqj2xAILsCRkKU4XyuY5N6DVSyhBROZdxzcvag6TuDmjsqlcXk4208ZgEw56UHNGjLwar5u/oFUX3cmFhg= X-MS-TrafficTypeDiagnostic: DM5PR07MB3498: X-Microsoft-Exchange-Diagnostics: 1;DM5PR07MB3498;20: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;4:vmalK0Jh2avaAwSLNzrP2gD7lZDMvLSlILDmfY4uj2kmXgzK/1llT7HRXYovhw7JdB+DSFxlieBj3XYRjDMyDmIxPNOo1HTtyBbDTsXN7CU5efaypE7gIMqtijAiktt4KPDLz0ztV/Qqnf3L1lTNukyqQ5cuYadC51xblc18VH+EqapM8reap0lEkoH1WSEycjArNOSJObaEPZURQBuy6YRJxSOa9ePjZsXRMpyMXQFlgtQN4X4s9kobSCO1ruynYm8Zyv09wIhISFc4OcUtMg== X-Exchange-Antispam-Report-Test: UriScan:; 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>> + u64 lock = (u64)&res_mgr_info->rlock; >> + >> + __asm__ __volatile__( >> + ".set noreorder\n" >> + "1: ll %[tmp], 0(%[addr])\n" >> + " bnez %[tmp], 1b\n" >> + " li %[tmp], 1\n" >> + " sc %[tmp], 0(%[addr])\n" >> + " beqz %[tmp], 1b\n" >> + " nop\n" >> + ".set reorder\n" : >> + [tmp] "=&r"(tmp) : >> + [addr] "r"(lock) : >> + "memory"); >> +} >> + >> +static void res_mgr_unlock(void) >> +{ >> + u64 lock = (u64)&res_mgr_info->rlock; >> + >> + /* Wait until all resource operations finish before unlocking. */ >> + mb(); >> + __asm__ __volatile__( >> + "sw $0, 0(%[addr])\n" : : >> + [addr] "r"(lock) : >> + "memory"); >> + >> + /* Force a write buffer flush. */ >> + mb(); >> +} > > It would be good to add some justification for using your own locks, > rather than standard linux locks. Yes, I will add that. > > Is there anything specific to your hardware in this resource manager? > I'm just wondering if this should be generic, put somewhere in lib. Or > maybe there is already something generic, and you should be using it, > not re-inventing the wheel again. The systems built around this hardware may have other software running on CPUs that are not running the Linux kernel. The data structures used to arbitrate usage of shared system hardware resources use exactly these locking primitives, so they cannot be changed to use the Linux locking implementation de jour.