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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 1732FC4338F for ; Tue, 3 Aug 2021 00:58:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E78AA60F9C for ; Tue, 3 Aug 2021 00:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233176AbhHCA6q (ORCPT ); Mon, 2 Aug 2021 20:58:46 -0400 Received: from netrider.rowland.org ([192.131.102.5]:46723 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S233050AbhHCA6p (ORCPT ); Mon, 2 Aug 2021 20:58:45 -0400 Received: (qmail 350320 invoked by uid 1000); 2 Aug 2021 20:58:34 -0400 Date: Mon, 2 Aug 2021 20:58:34 -0400 From: Alan Stern To: Salah Triki Cc: Keith Packard , Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] usb: misc: chaoskey: get lock before calling usb_[disable|enable]_autosuspend() Message-ID: <20210803005834.GB349864@rowland.harvard.edu> References: <20210802222205.GA1389315@pc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210802222205.GA1389315@pc> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Aug 02, 2021 at 11:22:05PM +0100, Salah Triki wrote: > Based on the documentation of usb_[disable|enable]_autosuspend(), the > caller must hold udev's device lock. > > Signed-off-by: Salah Triki > --- > drivers/usb/misc/chaoskey.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c > index 87067c3d6109..8af00be7b9e8 100644 > --- a/drivers/usb/misc/chaoskey.c > +++ b/drivers/usb/misc/chaoskey.c > @@ -206,7 +206,9 @@ static int chaoskey_probe(struct usb_interface *interface, > if (!dev->hwrng_registered) > usb_err(interface, "Unable to register with hwrng"); > > + usb_lock_device(udev); > usb_enable_autosuspend(udev); > + usb_unlock_device(udev); Not needed (indeed, actively harmful). When this code runs it already holds the device lock, because it is part of a probe routine. Alan Stern