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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED, 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 77168C433E0 for ; Mon, 28 Dec 2020 14:27:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52DCC22AEC for ; Mon, 28 Dec 2020 14:27:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502407AbgL1O1m (ORCPT ); Mon, 28 Dec 2020 09:27:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:35058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2502201AbgL1O1M (ORCPT ); Mon, 28 Dec 2020 09:27:12 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id E145020791; Mon, 28 Dec 2020 14:26:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609165591; bh=ATe23Rm/TKgb1NJsGRPJI5SJrqxqys9GsDW0OyV0fIw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I9SQrE6vNHgp1/rQmOl53sC6LIb9OFOhKPgPjJzEyHBte1d+53id/F2EmFqo9vjmR 2k1nnsS13dCGkfZ3iCsp5ICW/Usjk0fc3riuhOPBWFIs7ZBnJOEUVAF9G7brLQBcl+ aSQRkGp1r/Y3THhsMGLNOnN+CDfnn2TZopdgOWrY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sebastian Andrzej Siewior , Johan Hovold Subject: [PATCH 5.10 586/717] USB: serial: keyspan_pda: fix write unthrottling Date: Mon, 28 Dec 2020 13:49:44 +0100 Message-Id: <20201228125048.990828703@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228125020.963311703@linuxfoundation.org> References: <20201228125020.963311703@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johan Hovold commit 320f9028c7873c3c7710e8e93e5c979f4c857490 upstream. The driver did not update its view of the available device buffer space until write() was called in task context. This meant that write_room() would return 0 even after the device had sent a write-unthrottle notification, something which could lead to blocked writers not being woken up (e.g. when using OPOST). Note that we must also request an unthrottle notification is case a write() request fills the device buffer exactly. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable Acked-by: Sebastian Andrzej Siewior Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/keyspan_pda.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) --- a/drivers/usb/serial/keyspan_pda.c +++ b/drivers/usb/serial/keyspan_pda.c @@ -40,6 +40,8 @@ #define DRIVER_AUTHOR "Brian Warner " #define DRIVER_DESC "USB Keyspan PDA Converter driver" +#define KEYSPAN_TX_THRESHOLD 16 + struct keyspan_pda_private { int tx_room; int tx_throttled; @@ -110,7 +112,7 @@ static void keyspan_pda_request_unthrott 7, /* request_unthrottle */ USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_OUT, - 16, /* value: threshold */ + KEYSPAN_TX_THRESHOLD, 0, /* index */ NULL, 0, @@ -129,6 +131,8 @@ static void keyspan_pda_rx_interrupt(str int retval; int status = urb->status; struct keyspan_pda_private *priv; + unsigned long flags; + priv = usb_get_serial_port_data(port); switch (status) { @@ -171,7 +175,10 @@ static void keyspan_pda_rx_interrupt(str case 1: /* modemline change */ break; case 2: /* tx unthrottle interrupt */ + spin_lock_irqsave(&port->lock, flags); priv->tx_throttled = 0; + priv->tx_room = max(priv->tx_room, KEYSPAN_TX_THRESHOLD); + spin_unlock_irqrestore(&port->lock, flags); /* queue up a wakeup at scheduler time */ usb_serial_port_softint(port); break; @@ -505,7 +512,8 @@ static int keyspan_pda_write(struct tty_ goto exit; } } - if (count > priv->tx_room) { + + if (count >= priv->tx_room) { /* we're about to completely fill the Tx buffer, so we'll be throttled afterwards. */ count = priv->tx_room; @@ -560,14 +568,17 @@ static void keyspan_pda_write_bulk_callb static int keyspan_pda_write_room(struct tty_struct *tty) { struct usb_serial_port *port = tty->driver_data; - struct keyspan_pda_private *priv; - priv = usb_get_serial_port_data(port); - /* used by n_tty.c for processing of tabs and such. Giving it our - conservative guess is probably good enough, but needs testing by - running a console through the device. */ - return priv->tx_room; -} + struct keyspan_pda_private *priv = usb_get_serial_port_data(port); + unsigned long flags; + int room = 0; + + spin_lock_irqsave(&port->lock, flags); + if (test_bit(0, &port->write_urbs_free) && !priv->tx_throttled) + room = priv->tx_room; + spin_unlock_irqrestore(&port->lock, flags); + return room; +} static int keyspan_pda_chars_in_buffer(struct tty_struct *tty) {