From patchwork Wed Apr 7 10:28:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johan Hovold X-Patchwork-Id: 417174 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, URIBL_BLOCKED, 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 C5E5CC433ED for ; Wed, 7 Apr 2021 10:29:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87945613A7 for ; Wed, 7 Apr 2021 10:29:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237037AbhDGK3S (ORCPT ); Wed, 7 Apr 2021 06:29:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:46114 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233465AbhDGK3L (ORCPT ); Wed, 7 Apr 2021 06:29:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4119B61284; Wed, 7 Apr 2021 10:29:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617791342; bh=0f5iqAFTzVz/UUoG84WKx/vqS1eja/sTREPpFmtK6Zw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uV96icEZvQKAFD6EyJtKG8WL8/YnUIUV6q3ANMtyBgjssMzBQCfdZUebj9mJI/GqU Yo1ylv2aQjwVkKcRQ1p9VlOieD5KH6IPyds0njC/XkE2JA2fNandTDTt47RMCfMis9 hiYxAH7eShrnSwAlPTYKHB+okz5gwzvLS3TNdyUe+UY+jLHgeNTcSCvDQqwbedS6Ci kNz5r873zT9rFB0PwpwM3iYOYcb+b+HcTE1VbQ20AdC4fLLFbG506LJy8hXxsIT70G ireKO6D8KBlWRvO8kyDTwOCYhTWxIa2uH8qP4MDkpuMo/32NTASBo8200bbteCEsCr WzjWi2CNDCT0Q== Received: from johan by xi.lan with local (Exim 4.93.0.4) (envelope-from ) id 1lU5Qc-00004s-N9; Wed, 07 Apr 2021 12:28:54 +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 1/3] Revert "USB: cdc-acm: fix rounding error in TIOCSSERIAL" Date: Wed, 7 Apr 2021 12:28:43 +0200 Message-Id: <20210407102845.32720-2-johan@kernel.org> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20210407102845.32720-1-johan@kernel.org> References: <20210407102845.32720-1-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). 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 --- 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;