Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753802AbaGZTTu (ORCPT ); Sat, 26 Jul 2014 15:19:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34376 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754223AbaGZTNZ (ORCPT ); Sat, 26 Jul 2014 15:13:25 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tyler Hall , Oliver Hartkopp , Andre Naujoks , "David S. Miller" Subject: [PATCH 3.15 036/109] slcan: Port write_wakeup deadlock fix from slip Date: Sat, 26 Jul 2014 12:01:58 -0700 Message-Id: <20140726190224.918628639@linuxfoundation.org> X-Mailer: git-send-email 2.0.2 In-Reply-To: <20140726190223.834037485@linuxfoundation.org> References: <20140726190223.834037485@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tyler Hall [ Upstream commit a8e83b17536aad603fbeae4c460f2da0ee9fe6ed ] The commit "slip: Fix deadlock in write_wakeup" fixes a deadlock caused by a change made in both slcan and slip. This is a direct port of that fix. Signed-off-by: Tyler Hall Cc: Oliver Hartkopp Cc: Andre Naujoks Cc: David S. Miller Cc: linux-kernel@vger.kernel.org Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/slcan.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) --- a/drivers/net/can/slcan.c +++ b/drivers/net/can/slcan.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #include @@ -85,6 +86,7 @@ struct slcan { struct tty_struct *tty; /* ptr to TTY structure */ struct net_device *dev; /* easy for intr handling */ spinlock_t lock; + struct work_struct tx_work; /* Flushes transmit buffer */ /* These are pointers to the malloc()ed frame buffers. */ unsigned char rbuff[SLC_MTU]; /* receiver buffer */ @@ -309,36 +311,46 @@ static void slc_encaps(struct slcan *sl, sl->dev->stats.tx_bytes += cf->can_dlc; } -/* - * Called by the driver when there's room for more data. If we have - * more packets to send, we send them here. - */ -static void slcan_write_wakeup(struct tty_struct *tty) +/* Write out any remaining transmit buffer. Scheduled when tty is writable */ +static void slcan_transmit(struct work_struct *work) { + struct slcan *sl = container_of(work, struct slcan, tx_work); int actual; - struct slcan *sl = (struct slcan *) tty->disc_data; + spin_lock_bh(&sl->lock); /* First make sure we're connected. */ - if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) + if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) { + spin_unlock_bh(&sl->lock); return; + } - spin_lock_bh(&sl->lock); if (sl->xleft <= 0) { /* Now serial buffer is almost free & we can start * transmission of another packet */ sl->dev->stats.tx_packets++; - clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); + clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); spin_unlock_bh(&sl->lock); netif_wake_queue(sl->dev); return; } - actual = tty->ops->write(tty, sl->xhead, sl->xleft); + actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft); sl->xleft -= actual; sl->xhead += actual; spin_unlock_bh(&sl->lock); } +/* + * Called by the driver when there's room for more data. + * Schedule the transmit. + */ +static void slcan_write_wakeup(struct tty_struct *tty) +{ + struct slcan *sl = tty->disc_data; + + schedule_work(&sl->tx_work); +} + /* Send a can_frame to a TTY queue. */ static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev) { @@ -528,6 +540,7 @@ static struct slcan *slc_alloc(dev_t lin sl->magic = SLCAN_MAGIC; sl->dev = dev; spin_lock_init(&sl->lock); + INIT_WORK(&sl->tx_work, slcan_transmit); slcan_devs[i] = dev; return sl; @@ -626,8 +639,12 @@ static void slcan_close(struct tty_struc if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) return; + spin_lock_bh(&sl->lock); tty->disc_data = NULL; sl->tty = NULL; + spin_unlock_bh(&sl->lock); + + flush_work(&sl->tx_work); /* Flush network side */ unregister_netdev(sl->dev); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/