From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941510AbcKOJrx (ORCPT ); Tue, 15 Nov 2016 04:47:53 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:34396 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941400AbcKOJrs (ORCPT ); Tue, 15 Nov 2016 04:47:48 -0500 Date: Tue, 15 Nov 2016 10:47:44 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: gregkh@linuxfoundation.org, keescook@chromium.org, will.deacon@arm.com, elena.reshetova@intel.com, arnd@arndb.de, tglx@linutronix.de, hpa@zytor.com, dave@progbits.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Message-ID: <20161115094744.GG3142@twins.programming.kicks-ass.net> References: <20161114173946.501528675@infradead.org> <20161114174446.832175072@infradead.org> <20161115084009.GB15734@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161115084009.GB15734@gmail.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 15, 2016 at 09:40:09AM +0100, Ingo Molnar wrote: > > * Peter Zijlstra wrote: > > > Provide refcount_t, an atomic_t like primitive built just for > > refcounting. > > > > It provides overflow and underflow checks as well as saturation > > semantics such that when it overflows, we'll never attempt to free it > > again, ever. > > > > Signed-off-by: Peter Zijlstra (Intel) > > --- > > include/linux/kref.h | 29 ++---- > > include/linux/refcount.h | 221 +++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 232 insertions(+), 18 deletions(-) > > I'd suggest splitting this patch into two parts: first patch introduces the > refcount.h facility, second patch changes over struct kref to the new facility. You're right, I was just really glad I got it to compile and didn't want to prod more at it. Should I also make a CONFIG knob that implements refcount_t with the 'normal' atomic_t primitives? And possibly another knob to toggle the BUG()s into WARN()s. With the full saturation semantics WARN() is a lot safer and will not corrupt kernel state as much.