On 16.06.2014 04:23, schrieb Tyler Hall:
> 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.
I don't know if it is still needed, but for the slcan part, you can add my:
Tested-by: Andre Naujoks <nauts...@gmail.com>
Regards
Andre
>
> Signed-off-by: Tyler Hall <tylerwh...@gmail.com>
> Cc: Oliver Hartkopp <socket...@hartkopp.net>
> Cc: Andre Naujoks <nauts...@gmail.com>
> Cc: David S. Miller <da...@davemloft.net>
> Cc: linux-kernel@vger.kernel.org
> ---
> 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 <linux/delay.h>
> #include <linux/init.h>
> #include <linux/kernel.h>
> +#include <linux/workqueue.h>
> #include <linux/can.h>
> #include <linux/can/skb.h>
>
> @@ -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);
>
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