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Date: Tue, 26 Feb 2013 20:47:30 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: Lai Jiangshan <eag0628@...il.com> CC: linux-doc@...r.kernel.org, peterz@...radead.org, fweisbec@...il.com, linux-kernel@...r.kernel.org, Michel Lespinasse <walken@...gle.com>, mingo@...nel.org, linux-arch@...r.kernel.org, linux@....linux.org.uk, xiaoguangrong@...ux.vnet.ibm.com, wangyun@...ux.vnet.ibm.com, paulmck@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com, linux-pm@...r.kernel.org, rusty@...tcorp.com.au, rostedt@...dmis.org, rjw@...k.pl, namhyung@...nel.org, tglx@...utronix.de, linux-arm-kernel@...ts.infradead.org, Lai Jiangshan <laijs@...fujitsu.com>, netdev@...r.kernel.org, oleg@...hat.com, vincent.guittot@...aro.org, sbw@....edu, tj@...nel.org, akpm@...ux-foundation.org, linuxppc-dev@...ts.ozlabs.org Subject: Re: [PATCH v6 04/46] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks On 02/26/2013 07:04 PM, Lai Jiangshan wrote: > On Tue, Feb 26, 2013 at 3:26 AM, Srivatsa S. Bhat > <srivatsa.bhat@...ux.vnet.ibm.com> wrote: >> Hi Lai, >> >> On 02/25/2013 09:23 PM, Lai Jiangshan wrote: >>> Hi, Srivatsa, >>> >>> The target of the whole patchset is nice for me. >> >> Cool! Thanks :-) >> >>> A question: How did you find out the such usages of >>> "preempt_disable()" and convert them? did all are converted? >>> >> >> Well, I scanned through the source tree for usages which implicitly >> disabled CPU offline and converted them over. > > How do you scan? could you show the way you scan the source tree. > I can follow your instructions for double checking. > Its nothing special. I grepped the source tree for anything dealing with cpu_online_mask or its derivatives and also for functions/constructs that rely on the cpumasks internally (eg: smp_call_function). Then I audited all such call-sites and converted them (if needed) accordingly. >> Its not limited to uses >> of preempt_disable() alone - even spin_locks, rwlocks, local_irq_disable() >> etc also help disable CPU offline. So I tried to dig out all such uses >> and converted them. However, since the merge window is open, a lot of >> new code is flowing into the tree. So I'll have to rescan the tree to >> see if there are any more places to convert. > > I remember some code has such assumption: > preempt_disable() (or something else) > //the code assume that the cpu_online_map can't be changed. > preempt_enable() > > It is very hard to find out all such kinds of assumptions and fixes them. > (I notice your code mainly fixes code around send_xxxx()) > The conversion can be carried out using the method I mentioned above. Regards, Srivatsa S. Bhat -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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