From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD9AFC388F9 for ; Mon, 16 Nov 2020 22:54:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 833852244C for ; Mon, 16 Nov 2020 22:54:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728625AbgKPWyJ (ORCPT ); Mon, 16 Nov 2020 17:54:09 -0500 Received: from mx2.suse.de ([195.135.220.15]:36744 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgKPWyJ (ORCPT ); Mon, 16 Nov 2020 17:54:09 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 61900ACC5; Mon, 16 Nov 2020 22:54:07 +0000 (UTC) Date: Mon, 16 Nov 2020 14:31:02 -0800 From: Davidlohr Bueso To: Johan Hovold Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH] USB: serial: mos7720: defer state restore to a workqueue Message-ID: <20201116223102.eliwt7uh5rkiiq5h@linux-p48b.lan> References: <20201102211450.5722-1-dave@stgolabs.net> <20201103204014.3ue37owcras6cx7p@linux-p48b.lan> <20201104110657.GW4085@localhost> <20201104162534.GY4085@localhost> <20201105001307.lelve65nif344cfs@linux-p48b.lan> <20201105082540.GA4085@localhost> <20201106061713.lgghl4xnvdmkvges@linux-p48b.lan> <20201113091443.GI4085@localhost> <20201114042725.ofs7zbzmxg32tbbi@linux-p48b.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 Nov 2020, Johan Hovold wrote: >On Fri, Nov 13, 2020 at 08:27:25PM -0800, Davidlohr Bueso wrote: >> @@ -1883,21 +1724,17 @@ static void mos7720_release(struct usb_serial *serial) >> if (mos_parport->msg_pending) >> wait_for_completion_timeout(&mos_parport->syncmsg_compl, >> msecs_to_jiffies(MOS_WDR_TIMEOUT)); >> + /* >> + * If delayed work is currently scheduled, wait for it to >> + * complete. This also implies barriers that ensure the >> + * below serial clearing is not hoisted above the ->work. >> + */ >> + cancel_work_sync(&mos_parport->work); > >As I mentioned, this needs to be done *after* deregistering the port or >you could theoretically end up with the work item being requeued. Hmm sorry yes I forgot to mention this. I was counting on the private_data already being null to prevent any new work being actually scheduled, so an incoming restore state, for example, would be a nop. > >Yes, the same applies for the "synchronous" requests, but that's a >preexisting issue. Per the above I also assumed sync requests were also safe as is. But I can certainly re-order things, how about: mos7720_release(): mos_parport->pp->private_data = NULL; parport_remove_port(mos_parport->pp); wait_for_completion_timeout(); cancel_work_sync(); usb_set_serial_data(serial, NULL); mos_parport->serial = NULL; parport_del_port(mos_parport->pp); kref_put(); Thanks, Davidlohr