From a8e83b17536aad603fbeae4c460f2da0ee9fe6ed Mon Sep 17 00:00:00 2001 From: Tyler Hall Date: Sun, 15 Jun 2014 22:23:17 -0400 Subject: [PATCH] slcan: Port write_wakeup deadlock fix from slip 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 --- drivers/net/can/slcan.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c index dcf9196..ea4d4f1 100644 --- 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, 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_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 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; @@ -626,8 +639,12 @@ 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); -- 2.7.4