Return-path: Received: from mail-wi0-f171.google.com ([209.85.212.171]:51507 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaFWM7n convert rfc822-to-8bit (ORCPT ); Mon, 23 Jun 2014 08:59:43 -0400 Received: by mail-wi0-f171.google.com with SMTP id n15so4287056wiw.16 for ; Mon, 23 Jun 2014 05:59:42 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1403526767.4418.24.camel@jlt4.sipsolutions.net> References: <1400767955-16313-1-git-send-email-michal.kazior@tieto.com> <1400767955-16313-3-git-send-email-michal.kazior@tieto.com> <1400769683.4174.25.camel@jlt4.sipsolutions.net> <1403524278.4418.19.camel@jlt4.sipsolutions.net> <1403526767.4418.24.camel@jlt4.sipsolutions.net> Date: Mon, 23 Jun 2014 14:59:42 +0200 Message-ID: (sfid-20140623_145947_390503_764913B9) Subject: Re: [PATCH 2/2] ath10k: make core registering async From: Michal Kazior To: Johannes Berg Cc: "ath10k@lists.infradead.org" , linux-wireless Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 23 June 2014 14:32, Johannes Berg wrote: > On Mon, 2014-06-23 at 14:17 +0200, Michal Kazior wrote: > >> > Seems like to fix it we just need to get a module reference though? Can >> > a module put() itself though? Hmmm. >> >> It seems some drivers use module_put(THIS_MODULE) and >> __module_get(THIS_MODULE), e.g. tun/tap driver. > > I don't see how this isn't racy in similar ways though? I think tun/tap uses it for different purposes. >> But does this bump up the module refcount in such a way that an >> in-progress rmmod will wait/block until the refcount reaches 0? > > It should, yes, but you race once you do module_put(), no? It's still racy, I agree. I don't see how device_release_driver() can be made work synchronously at all. It should, however, be perfectly fine if this was an async request to release a device/driver, right? Michał