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=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 17CEFC433E6 for ; Mon, 28 Dec 2020 13:19:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1639207C9 for ; Mon, 28 Dec 2020 13:18:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387534AbgL1NSk (ORCPT ); Mon, 28 Dec 2020 08:18:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:46886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731778AbgL1NSi (ORCPT ); Mon, 28 Dec 2020 08:18:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A2DF3206ED; Mon, 28 Dec 2020 13:18:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609161502; bh=5s+ayH5xSO+3HI4I6eAAxZcKK4J4aqp9MoUjWQlXeIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RiUP2C+q6T4XDWCgh7NS5hhNLNkwZbwuVmJ5QbQEmeuGqPkzFwtkFaedJ2H9MjEv/ aM0k6VSHrKYXjqnB5+wUqfnO+k9EuWfTuw3I9q3xUocKzh1J1JkROpO/l5Ke7rtzFx 2vM+vTk5j+7WNKAaaInGiuNM66YjmvCHZwdEvilU= 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 4.14 205/242] USB: serial: keyspan_pda: fix write unthrottling Date: Mon, 28 Dec 2020 13:50:10 +0100 Message-Id: <20201228124914.769521607@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124904.654293249@linuxfoundation.org> References: <20201228124904.654293249@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 @@ -44,6 +44,8 @@ #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; @@ -114,7 +116,7 @@ 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, @@ -133,6 +135,8 @@ 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) { @@ -175,7 +179,10 @@ 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; @@ -509,7 +516,8 @@ 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; @@ -564,14 +572,17 @@ 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) {