From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753735AbbJFUHn (ORCPT ); Tue, 6 Oct 2015 16:07:43 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:57667 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752924AbbJFUHl (ORCPT ); Tue, 6 Oct 2015 16:07:41 -0400 Date: Tue, 6 Oct 2015 22:07:25 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 07/13] rcu: Move preemption disabling out of __srcu_read_lock() Message-ID: <20151006200725.GV3604@twins.programming.kicks-ass.net> References: <20151006161305.GA9799@linux.vnet.ibm.com> <1444148028-11551-1-git-send-email-paulmck@linux.vnet.ibm.com> <1444148028-11551-7-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1444148028-11551-7-git-send-email-paulmck@linux.vnet.ibm.com> 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 On Tue, Oct 06, 2015 at 09:13:42AM -0700, Paul E. McKenney wrote: > Currently, __srcu_read_lock() cannot be invoked from restricted > environments because it contains calls to preempt_disable() and > preempt_enable(), both of which can invoke lockdep, which is a bad > idea in some restricted execution modes. This commit therefore moves > the preempt_disable() and preempt_enable() from __srcu_read_lock() > to srcu_read_lock(). It also inserts the preempt_disable() and > preempt_enable() around the call to __srcu_read_lock() in do_exit(). Did you not simply want to use: preempt_disable_notrace() ?