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=-18.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6C621C433FE for ; Fri, 11 Dec 2020 16:03:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F0E223137 for ; Fri, 11 Dec 2020 16:03:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437719AbgLKPRa (ORCPT ); Fri, 11 Dec 2020 10:17:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:41276 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437779AbgLKPRK (ORCPT ); Fri, 11 Dec 2020 10:17:10 -0500 Subject: patch "USB: serial: keyspan_pda: fix write unthrottling" added to usb-testing DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1607699790; bh=ClXvw17slQpT7fiLTqVOfxJ/5/MiWGFWNlJaYVNZdsI=; h=To:From:Date:From; b=qMW23d9J+QzjY/atfaYqEJDef+aVROz8tJnzNbBooGl54Fp2BX5qkJB05C0uouiOy ThcmrXbSSgZWJnulRdoLRgZ1XEoOO67GglBhbPO/BlOvvaoHNrZfK9L/Jk2Xf/7bER 25ddewPnsGHAHVVJh0IktP0VCGTfPTyK+G1nn0wA= To: johan@kernel.org, bigeasy@linutronix.de, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Fri, 11 Dec 2020 16:17:20 +0100 Message-ID: <1607699840133141@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled USB: serial: keyspan_pda: fix write unthrottling to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-testing branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will be merged to the usb-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From 320f9028c7873c3c7710e8e93e5c979f4c857490 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Sun, 25 Oct 2020 18:45:52 +0100 Subject: USB: serial: keyspan_pda: fix write unthrottling 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 --- drivers/usb/serial/keyspan_pda.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c index 781b6723379f..39ed3ad32365 100644 --- 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_unthrottle(struct work_struct *work) 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(struct urb *urb) 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(struct urb *urb) 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_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_callback(struct urb *urb) 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) { -- 2.29.2