From patchwork Mon Dec 28 12:50:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 353191 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 1054FC43381 for ; Mon, 28 Dec 2020 15:58:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CF0BC229C6 for ; Mon, 28 Dec 2020 15:58:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391464AbgL1P4x (ORCPT ); Mon, 28 Dec 2020 10:56:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:36062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389398AbgL1Nfk (ORCPT ); Mon, 28 Dec 2020 08:35:40 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id B55CA20728; Mon, 28 Dec 2020 13:34:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609162499; bh=LO8k7uszt+2lnUZpmP53uFdzZB7CaRJtMeWahAVxUrQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oxdwwzp7nL5ydtdWb9Z1sACDcAI0hcXsPe11rpq6nZ6L+Bf8WYnhdS/s7JcknbrAe iI2DsPoBFWSSL5d+1+3zDGb+DL6iGf5KQgqfb5Fk3HG9Y0t2MvawOd+E+plbdhg9rB mtbUT12FDz6TeTiy88Sv5NO7R4P+lXoV2Mc/dlIQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johan Hovold Subject: [PATCH 4.19 290/346] USB: serial: digi_acceleport: fix write-wakeup deadlocks Date: Mon, 28 Dec 2020 13:50:09 +0100 Message-Id: <20201228124933.796044761@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124919.745526410@linuxfoundation.org> References: <20201228124919.745526410@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Johan Hovold commit 5098e77962e7c8947f87bd8c5869c83e000a522a upstream. The driver must not call tty_wakeup() while holding its private lock as line disciplines are allowed to call back into write() from write_wakeup(), leading to a deadlock. Also remove the unneeded work struct that was used to defer wakeup in order to work around a possible race in ancient times (see comment about n_tty write_chan() in commit 14b54e39b412 ("USB: serial: remove changelogs and old todo entries")). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/digi_acceleport.c | 45 ++++++++++------------------------- 1 file changed, 13 insertions(+), 32 deletions(-) --- a/drivers/usb/serial/digi_acceleport.c +++ b/drivers/usb/serial/digi_acceleport.c @@ -19,7 +19,6 @@ #include #include #include -#include #include #include #include @@ -198,14 +197,12 @@ struct digi_port { int dp_throttle_restart; wait_queue_head_t dp_flush_wait; wait_queue_head_t dp_close_wait; /* wait queue for close */ - struct work_struct dp_wakeup_work; struct usb_serial_port *dp_port; }; /* Local Function Declarations */ -static void digi_wakeup_write_lock(struct work_struct *work); static int digi_write_oob_command(struct usb_serial_port *port, unsigned char *buf, int count, int interruptible); static int digi_write_inb_command(struct usb_serial_port *port, @@ -356,26 +353,6 @@ __releases(lock) return timeout; } - -/* - * Digi Wakeup Write - * - * Wake up port, line discipline, and tty processes sleeping - * on writes. - */ - -static void digi_wakeup_write_lock(struct work_struct *work) -{ - struct digi_port *priv = - container_of(work, struct digi_port, dp_wakeup_work); - struct usb_serial_port *port = priv->dp_port; - unsigned long flags; - - spin_lock_irqsave(&priv->dp_port_lock, flags); - tty_port_tty_wakeup(&port->port); - spin_unlock_irqrestore(&priv->dp_port_lock, flags); -} - /* * Digi Write OOB Command * @@ -987,6 +964,7 @@ static void digi_write_bulk_callback(str unsigned long flags; int ret = 0; int status = urb->status; + bool wakeup; /* port and serial sanity check */ if (port == NULL || (priv = usb_get_serial_port_data(port)) == NULL) { @@ -1013,6 +991,7 @@ static void digi_write_bulk_callback(str } /* try to send any buffered data on this port */ + wakeup = true; spin_lock_irqsave(&priv->dp_port_lock, flags); priv->dp_write_urb_in_use = 0; if (priv->dp_out_buf_len > 0) { @@ -1028,19 +1007,18 @@ static void digi_write_bulk_callback(str if (ret == 0) { priv->dp_write_urb_in_use = 1; priv->dp_out_buf_len = 0; + wakeup = false; } } - /* wake up processes sleeping on writes immediately */ - tty_port_tty_wakeup(&port->port); - /* also queue up a wakeup at scheduler time, in case we */ - /* lost the race in write_chan(). */ - schedule_work(&priv->dp_wakeup_work); - spin_unlock_irqrestore(&priv->dp_port_lock, flags); + if (ret && ret != -EPERM) dev_err_console(port, "%s: usb_submit_urb failed, ret=%d, port=%d\n", __func__, ret, priv->dp_port_num); + + if (wakeup) + tty_port_tty_wakeup(&port->port); } static int digi_write_room(struct tty_struct *tty) @@ -1240,7 +1218,6 @@ static int digi_port_init(struct usb_ser init_waitqueue_head(&priv->dp_transmit_idle_wait); init_waitqueue_head(&priv->dp_flush_wait); init_waitqueue_head(&priv->dp_close_wait); - INIT_WORK(&priv->dp_wakeup_work, digi_wakeup_write_lock); priv->dp_port = port; init_waitqueue_head(&port->write_wait); @@ -1509,13 +1486,14 @@ static int digi_read_oob_callback(struct rts = C_CRTSCTS(tty); if (tty && opcode == DIGI_CMD_READ_INPUT_SIGNALS) { + bool wakeup = false; + spin_lock_irqsave(&priv->dp_port_lock, flags); /* convert from digi flags to termiox flags */ if (val & DIGI_READ_INPUT_SIGNALS_CTS) { priv->dp_modem_signals |= TIOCM_CTS; - /* port must be open to use tty struct */ if (rts) - tty_port_tty_wakeup(&port->port); + wakeup = true; } else { priv->dp_modem_signals &= ~TIOCM_CTS; /* port must be open to use tty struct */ @@ -1534,6 +1512,9 @@ static int digi_read_oob_callback(struct priv->dp_modem_signals &= ~TIOCM_CD; spin_unlock_irqrestore(&priv->dp_port_lock, flags); + + if (wakeup) + tty_port_tty_wakeup(&port->port); } else if (opcode == DIGI_CMD_TRANSMIT_IDLE) { spin_lock_irqsave(&priv->dp_port_lock, flags); priv->dp_transmit_idle = 1;