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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED 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 692E2C433DB for ; Mon, 28 Dec 2020 08:42:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C97B20897 for ; Mon, 28 Dec 2020 08:42:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726462AbgL1ImV (ORCPT ); Mon, 28 Dec 2020 03:42:21 -0500 Received: from wforward3-smtp.messagingengine.com ([64.147.123.22]:40349 "EHLO wforward3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbgL1ImV (ORCPT ); Mon, 28 Dec 2020 03:42:21 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.west.internal (Postfix) with ESMTP id 8683D757; Mon, 28 Dec 2020 03:41:35 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Mon, 28 Dec 2020 03:41:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=4np9Ce XG1ZyKDn9RmuWWXU0ni+YkTXNwXZeEHIaqcRQ=; b=LIhBt/O6jge9OL0qGGtsjW qJspdj7j7njp1GtadgzKh1CP8euSBzhuKkVXs7mCazGzw+1PAfB2SNyBxuHCfHN0 IaFHoFLo65kc0b8LeoKQrQNFFkHLZdEuPrkBT24JTSpUWWXfEcNRznsrMU28JVXF kg4bZ/SGpvAl4Bx8yZ0gIs96bGrEIqRjbgSMpoKc3lF6DQbzm/Xk7XAuo09uCpwI CMrHgMDp4Q+3BZYmvRFg+EMb2SoWJwwXypElunJS2MLIfWn1Dww3qEiuEsiDmRWI RSexwsNr9pxXmlB74AryXRK0TkpuFjPks//QVy6aZ8kW4djy93zhAwqei2xS9Rpg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedrvddukedguddvudcutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfgh necuuegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertd dttdflnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdho rhhgqeenucggtffrrghtthgvrhhnpeeiteevheeuvdfhtdfgvdeiieehheefleevveehje duteevueevledujeejgfetheenucfkphepkeefrdekiedrjeegrdeigeenucevlhhushht vghrufhiiigvpedvnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhh drtghomh X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id B6662108005C; Mon, 28 Dec 2020 03:41:34 -0500 (EST) Subject: FAILED: patch "[PATCH] USB: serial: digi_acceleport: fix write-wakeup deadlocks" failed to apply to 4.9-stable tree To: johan@kernel.org, gregkh@linuxfoundation.org Cc: From: Date: Mon, 28 Dec 2020 09:42:49 +0100 Message-ID: <160914496955152@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 The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5098e77962e7c8947f87bd8c5869c83e000a522a Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 26 Oct 2020 11:43:06 +0100 Subject: [PATCH] USB: serial: digi_acceleport: fix write-wakeup deadlocks 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 diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c index 016e7dec3196..968e08cdcb09 100644 --- 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 * @@ -985,6 +962,7 @@ static void digi_write_bulk_callback(struct urb *urb) 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) { @@ -1011,6 +989,7 @@ static void digi_write_bulk_callback(struct urb *urb) } /* 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) { @@ -1026,19 +1005,18 @@ static void digi_write_bulk_callback(struct urb *urb) 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) @@ -1238,7 +1216,6 @@ static int digi_port_init(struct usb_serial_port *port, unsigned port_num) 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); @@ -1507,13 +1484,14 @@ static int digi_read_oob_callback(struct urb *urb) 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 */ @@ -1532,6 +1510,9 @@ static int digi_read_oob_callback(struct urb *urb) 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;