From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751814AbaKFCUP (ORCPT ); Wed, 5 Nov 2014 21:20:15 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38978 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751762AbaKFCUL (ORCPT ); Wed, 5 Nov 2014 21:20:11 -0500 Date: Wed, 5 Nov 2014 18:20:10 -0800 From: Greg KH To: "Winkler, Tomas" Cc: "arnd@arndb.de" , "linux-kernel@vger.kernel.org" Subject: Re: [char-misc-next V3] mei: add reference counting for me clients Message-ID: <20141106022010.GD17253@kroah.com> References: <1415004125-5467-1-git-send-email-tomas.winkler@intel.com> <20141103235439.GA26158@kroah.com> <5B8DA87D05A7694D9FA63FD143655C1B1C493153@HASMSX106.ger.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5B8DA87D05A7694D9FA63FD143655C1B1C493153@HASMSX106.ger.corp.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 04, 2014 at 05:22:51AM +0000, Winkler, Tomas wrote: > > > > On Mon, Nov 03, 2014 at 10:42:05AM +0200, Tomas Winkler wrote: > > > To support dynamic addition/remove we add reference > > > counter. > > > > What is keeping two different threads / cpus from grabbing a reference > > at the same time the other one is dropping it? > > > > You have a list here, with no locking, right? You also don't have any > > locking for your kref, which isn't good at all... > > > > Please audit and fix up. > > Of course there is a lock, it wouldn't work at all. It is not explicit > but we run under device_lock mutex. Please make it explicit :) thanks, greg k-h