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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C525C433F5 for ; Thu, 30 Dec 2021 10:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238759AbhL3K4i (ORCPT ); Thu, 30 Dec 2021 05:56:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235057AbhL3K4h (ORCPT ); Thu, 30 Dec 2021 05:56:37 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A1C5C061574 for ; Thu, 30 Dec 2021 02:56:37 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 18A2661653 for ; Thu, 30 Dec 2021 10:56:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBEFEC36AEA; Thu, 30 Dec 2021 10:56:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1640861796; bh=A2T/Y+Ql9k2bDuHwfMm6vLzaSZVqqfDo2M66dRFPWzI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=T7ns7QvxczrnJAaIWB3vRy66toNLXSgpNTwLjtG2Ku8BIKW3wI+X4QAwwERQRAECJ Td6hiQUWaaKQHhyBxWT8yJ3NKkYBQntyUDX6PBzFAqnbTcpF01XY29XyL8aT99Qu0j oLQOtSbSv4/ZKi0yr938BwyOMtF7lj+F+wEZrgQU= Date: Thu, 30 Dec 2021 11:56:33 +0100 From: Greg KH To: Paulo Miguel Almeida Cc: realwakka@gmail.com, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] staging: pi433: add comment to rx_lock mutex definition Message-ID: References: <20211222215615.GA9361@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211222215615.GA9361@localhost.localdomain> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 23, 2021 at 10:56:15AM +1300, Paulo Miguel Almeida wrote: > Checkpatch reports: CHECK: struct mutex definition without comment. > Fix this by documenting what rx_mutex struct is used for in pi433 driver. > > Signed-off-by: Paulo Miguel Almeida > --- > v2: ellaborate on reasons why the mutex lock is used in the driver (Req: Greg k-h) > v1: https://lore.kernel.org/lkml/20211222093626.GA13332@localhost.localdomain/ > --- > drivers/staging/pi433/pi433_if.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c > index 29bd37669059..1cd3d5f2df2a 100644 > --- a/drivers/staging/pi433/pi433_if.c > +++ b/drivers/staging/pi433/pi433_if.c > @@ -92,6 +92,17 @@ struct pi433_device { > u32 rx_bytes_to_drop; > u32 rx_bytes_dropped; > unsigned int rx_position; > + /* > + * rx_lock is used to avoid race-conditions that can be triggered from userspace. > + * > + * For instance, if a program in userspace is reading the char device > + * allocated in this module then another program won't be able to change RX > + * configuration of the RF69 hardware module via ioctl and vice versa. > + * > + * utilization summary: > + * - pi433_read: blocks are read until rx read something (up to the buffer size) > + * - pi433_ioctl: during pending read request, change of config not allowed > + */ This is nice, but way too specific, and will quickly get out-of-date. How about something simple like: /* Protects all rx_* variable accesses */ thanks, greg k-h