From patchwork Thu Apr 8 13:16:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 12191051 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 74661C43460 for ; Thu, 8 Apr 2021 13:16:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 563F361159 for ; Thu, 8 Apr 2021 13:16:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231655AbhDHNQe (ORCPT ); Thu, 8 Apr 2021 09:16:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:36550 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231255AbhDHNQ2 (ORCPT ); Thu, 8 Apr 2021 09:16:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B06F461153; Thu, 8 Apr 2021 13:16:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617887776; bh=d3QIU2csiNcJOLhdhvMefuw6/6a+Kk8J/zx9o70Jpps=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Uh8hPpWVU5FMBgvNilxKuYOwn9YjfqX36+j/9INbaLI/SFniaEjUPvTSrDSkK0jsw 0AvOzuI3LpG+S/7BIqkjUk54KQVts84ymLFz1xx7WbAl118XMuByWMXb/sA9bG6QIr A/5hCFZw3sxdlyg87QbCW6jvYuzcztYI1U9onCfqcUAXytL3EF/e1A2mlIHBywVulQ XJnpqOvT7M6LQpxGQT9P714cWxD2ncacZLCd6ASSkB8M/2E8bt3G9d4veSRKPNfCIz qB3J1YKvbnqj91qkaQ+BAsIEHuqpmEAVpXleYlOJybzM8yi8aQMNtFwLJNJXJPLi0S oRKh1qYVG+jXQ== Received: from johan by xi.lan with local (Exim 4.93.0.4) (envelope-from ) id 1lUUW4-0007Hi-FQ; Thu, 08 Apr 2021 15:16:12 +0200 From: Johan Hovold To: Greg Kroah-Hartman Cc: Oliver Neukum , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold , Anthony Mallet , stable@vger.kernel.org Subject: [PATCH v2 1/3] Revert "USB: cdc-acm: fix rounding error in TIOCSSERIAL" Date: Thu, 8 Apr 2021 15:16:00 +0200 Message-Id: <20210408131602.27956-2-johan@kernel.org> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20210408131602.27956-1-johan@kernel.org> References: <20210408131602.27956-1-johan@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org This reverts commit b401f8c4f492cbf74f3f59c9141e5be3071071bb. The offending commit claimed that trying to set the values reported back by TIOCGSERIAL as a regular user could result in an -EPERM error when HZ is 250, but that was never the case. With HZ=250, the default 0.5 second value of close_delay is converted to 125 jiffies when set and is converted back to 50 centiseconds by TIOCGSERIAL as expected (not 12 cs as was claimed, even if that was the case before an earlier fix). Comparing the internal current and new jiffies values is just fine to determine if the value is about to change so drop the bogus workaround (which was also backported to stable). For completeness: With different default values for these parameters or with a HZ value not divisible by two, the lack of rounding when setting the default values in tty_port_init() could result in an -EPERM being returned, but this is hardly something we need to worry about. Cc: Anthony Mallet Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Acked-by: Oliver Neukum --- drivers/usb/class/cdc-acm.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 3fda1ec961d7..96e221803fa6 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -942,7 +942,6 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss) { struct acm *acm = tty->driver_data; unsigned int closing_wait, close_delay; - unsigned int old_closing_wait, old_close_delay; int retval = 0; close_delay = msecs_to_jiffies(ss->close_delay * 10); @@ -950,17 +949,11 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss) ASYNC_CLOSING_WAIT_NONE : msecs_to_jiffies(ss->closing_wait * 10); - /* we must redo the rounding here, so that the values match */ - old_close_delay = jiffies_to_msecs(acm->port.close_delay) / 10; - old_closing_wait = acm->port.closing_wait == ASYNC_CLOSING_WAIT_NONE ? - ASYNC_CLOSING_WAIT_NONE : - jiffies_to_msecs(acm->port.closing_wait) / 10; - mutex_lock(&acm->port.mutex); if (!capable(CAP_SYS_ADMIN)) { - if ((ss->close_delay != old_close_delay) || - (ss->closing_wait != old_closing_wait)) + if ((close_delay != acm->port.close_delay) || + (closing_wait != acm->port.closing_wait)) retval = -EPERM; else retval = -EOPNOTSUPP;