From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 9935BB6F07 for ; Tue, 12 Jan 2010 13:25:39 +1100 (EST) Subject: Re: [PATCH] Make cpu hotplug driver lock part of ppc_md From: Benjamin Herrenschmidt To: Nathan Fontenot In-Reply-To: <4B322DD6.60801@austin.ibm.com> References: <4B30DB8B.3030305@austin.ibm.com> <1261520982.17348.8.camel@concordia> <4B322DD6.60801@austin.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 12 Jan 2010 13:23:16 +1100 Message-ID: <1263262996.724.176.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Andreas Schwab List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > The intention of the cpu_hotplug_driver_locks to add additional serialization > during cpu hotplug operations. For pseries this is used during DLPAR of cpu > operations so that cpu hotplug actions cannot be initiated whiloe a DLPAR > operation is in flight. For example, during DLPAR add we take the lock while > acquiring the cpu from firmware and updating the device tree with the new > cpu information, after which we hotplug add the cpu to the system. > > There is nothing harmless about taking the lock on all platforms, I was just > trying to avoid taking the lock if the additional serialization is not needed. > > > > > If so, you could just make the mutex available to all powerpc code, and > > rename it, and then we wouldn't need all this jiggery pokery just to > > take & release a lock. > > I can make the lock available to all powerpc code and not go through the > ppc_md struct, it makes no difference to me personally. Of course this would > make all that fun pokery jiggery go away :) Yeah, Michael is right, just make it global to powerpc, it should make things simpler. Cheers, Ben.