From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Srivatsa S. Bhat" Subject: Re: [PATCH v6 04/46] percpu_rwlock: Implement the core design of Per-CPU Reader-Writer Locks Date: Mon, 18 Feb 2013 22:16:05 +0530 Message-ID: <51225ACD.3080100@linux.vnet.ibm.com> References: <20130218123714.26245.61816.stgit@srivatsabhat.in.ibm.com> <20130218123856.26245.46705.stgit@srivatsabhat.in.ibm.com> <5122551E.1080703@linux.vnet.ibm.com> <1361205087.23152.159.camel@gandalf.local.home> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1361205087.23152.159.camel@gandalf.local.home> Sender: linux-doc-owner@vger.kernel.org To: Steven Rostedt Cc: Michel Lespinasse , tglx@linutronix.de, peterz@infradead.org, tj@kernel.org, oleg@redhat.com, paulmck@linux.vnet.ibm.com, rusty@rustcorp.com.au, mingo@kernel.org, akpm@linux-foundation.org, namhyung@kernel.org, wangyun@linux.vnet.ibm.com, xiaoguangrong@linux.vnet.ibm.com, rjw@sisk.pl, sbw@mit.edu, fweisbec@gmail.com, linux@arm.linux.org.uk, nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, vincent.guittot@linaro.org List-Id: linux-pm@vger.kernel.org On 02/18/2013 10:01 PM, Steven Rostedt wrote: > On Mon, 2013-02-18 at 21:51 +0530, Srivatsa S. Bhat wrote: >> Hi Michel, > >> Yes.. I don't think we can avoid that. Moreover, since we _want_ unfair >> reader/writer semantics to allow flexible locking rules and guarantee >> deadlock-safety, having a recursive reader side is not even an issue, IMHO. > > Recursive unfair reader lock may guarantee deadlock-safety, but > remember, it adds a higher probability of live-locking the write_lock. > Which is another argument to keep this separate to cpu hotplug only. > True. Regards, Srivatsa S. Bhat