Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753650Ab3IIQWs (ORCPT ); Mon, 9 Sep 2013 12:22:48 -0400 Received: from merlin.infradead.org ([205.233.59.134]:55797 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751402Ab3IIQWr (ORCPT ); Mon, 9 Sep 2013 12:22:47 -0400 Date: Mon, 9 Sep 2013 18:21:56 +0200 From: Peter Zijlstra To: Frederic Weisbecker Cc: Steven Rostedt , "Paul E. McKenney" , Eric Dumazet , linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, sbw@mit.edu Subject: Re: [PATCH] rcu: Is it safe to enter an RCU read-side critical section? Message-ID: <20130909162156.GG26785@twins.programming.kicks-ass.net> References: <20130906185927.GE2706@somewhere> <20130909105347.GK31370@twins.programming.kicks-ass.net> <20130909121329.GA16280@somewhere> <20130909083926.3eceebef@gandalf.local.home> <20130909124547.GB16280@somewhere> <20130909085504.2ddd7e69@gandalf.local.home> <20130909130851.GC16280@somewhere> <20130909092142.05780991@gandalf.local.home> <20130909092917.0c99b71a@gandalf.local.home> <20130909144037.GH16280@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130909144037.GH16280@somewhere> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 649 Lines: 16 On Mon, Sep 09, 2013 at 04:40:38PM +0200, Frederic Weisbecker wrote: > > If the state migrates with a task from one CPU to another, it's a task > > state. > > This applies to preempt_count as well. This is in fact true. Its something I'd like to cure, but currently the PREEMPT_ACTIVE state makes this so. Hence the need to save/restore the per-cpu preempt state in the per-cpu preempt_count patches. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/