Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755571AbaG3Mio (ORCPT ); Wed, 30 Jul 2014 08:38:44 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:36677 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752800AbaG3MP1 (ORCPT ); Wed, 30 Jul 2014 08:15:27 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Tyler Hall , Oliver Hartkopp , Andre Naujoks , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 32/94] slcan: Port write_wakeup deadlock fix from slip Date: Wed, 30 Jul 2014 14:14:21 +0200 Message-Id: X-Mailer: git-send-email 2.0.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tyler Hall 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ 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: Jiri Slaby --- drivers/net/can/slcan.c | 41 +++++++++++++++++++++++++++++------------ 1 file changed, 29 insertions(+), 12 deletions(-) diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c index 25377e547f9b..3c28d1f187c0 100644 --- a/drivers/net/can/slcan.c +++ b/drivers/net/can/slcan.c @@ -54,6 +54,7 @@ #include #include #include +#include #include #include @@ -87,6 +88,7 @@ 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 */ @@ -311,34 +313,44 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf) 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(&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); - spin_unlock(&sl->lock); + 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(&sl->lock); + 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. */ @@ -524,6 +536,7 @@ static struct slcan *slc_alloc(dev_t line) 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; @@ -622,8 +635,12 @@ static void slcan_close(struct tty_struct *tty) 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); -- 2.0.1 -- 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/