From: Tyler Hall <tylerwhall@xxxxxxxxx>
This patch has been added to the 3.12 stable tree. If you have any
objections, please let us 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 <tylerwhall@xxxxxxxxx>
Cc: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
Cc: Andre Naujoks <nautsch2@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
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 <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/workqueue.h>
#include <linux/can.h>
#include <linux/can/skb.h>
@@ -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
--
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