4 files changed, 33 insertions, 16 deletions

diff --git a/drivers/net/slip/Kconfig b/drivers/net/slip/Kconfig
index 211b160e4e9..48e68714eef 100644
--- a/drivers/net/slip/Kconfig
+++ b/drivers/net/slip/Kconfig
@@ -4,6 +4,7 @@
 
 config SLIP
 	tristate "SLIP (serial line) support"
+	depends on TTY
 	---help---
 	  Say Y if you intend to use SLIP or CSLIP (compressed SLIP) to
 	  connect to your Internet service provider or to connect to some
diff --git a/drivers/net/slip/slhc.c b/drivers/net/slip/slhc.c
index 0a0a6643cf3..1252d9c726a 100644
--- a/drivers/net/slip/slhc.c
+++ b/drivers/net/slip/slhc.c
@@ -75,7 +75,6 @@
 #include <linux/skbuff.h>
 #include <net/sock.h>
 #include <linux/timer.h>
-#include <asm/system.h>
 #include <asm/uaccess.h>
 #include <net/checksum.h>
 #include <asm/unaligned.h>
diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
index ba08341fb92..87526443841 100644
--- a/drivers/net/slip/slip.c
+++ b/drivers/net/slip/slip.c
@@ -64,7 +64,6 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 
-#include <asm/system.h>
 #include <asm/uaccess.h>
 #include <linux/bitops.h>
 #include <linux/sched.h>
@@ -84,6 +83,7 @@
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 #include "slip.h"
 #ifdef CONFIG_INET
 #include <linux/ip.h>
@@ -391,10 +391,10 @@ static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 #endif
 #ifdef CONFIG_SLIP_MODE_SLIP6
 	if (sl->mode & SL_MODE_SLIP6)
-		count = slip_esc6(p, (unsigned char *) sl->xbuff, len);
+		count = slip_esc6(p, sl->xbuff, len);
 	else
 #endif
-		count = slip_esc(p, (unsigned char *) sl->xbuff, len);
+		count = slip_esc(p, sl->xbuff, len);
 
 	/* Order of next two lines is *very* important.
 	 * When we are sending a little amount of data,
@@ -417,31 +417,44 @@ static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
 #endif
 }
 
-/*
- * Called by the driver when there's room for more data.  If we have
- * more packets to send, we send them here.
- */
-static void slip_write_wakeup(struct tty_struct *tty)
+/* Write out any remaining transmit buffer. Scheduled when tty is writable */
+static void slip_transmit(struct work_struct *work)
 {
+	struct slip *sl = container_of(work, struct slip, tx_work);
 	int actual;
-	struct slip *sl = tty->disc_data;
 
+	spin_lock_bh(&sl->lock);
 	/* First make sure we're connected. */
-	if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
+	if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
+		spin_unlock_bh(&sl->lock);
 		return;
+	}
 
 	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);
 		sl_unlock(sl);
 		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 slip_write_wakeup(struct tty_struct *tty)
+{
+	struct slip *sl = tty->disc_data;
+
+	schedule_work(&sl->tx_work);
 }
 
 static void sl_tx_timeout(struct net_device *dev)
@@ -747,6 +760,7 @@ static struct slip *sl_alloc(dev_t line)
 	sl->magic       = SLIP_MAGIC;
 	sl->dev	      	= dev;
 	spin_lock_init(&sl->lock);
+	INIT_WORK(&sl->tx_work, slip_transmit);
 	sl->mode        = SL_MODE_DEFAULT;
 #ifdef CONFIG_SLIP_SMART
 	/* initialize timer_list struct */
@@ -870,8 +884,12 @@ static void slip_close(struct tty_struct *tty)
 	if (!sl || sl->magic != SLIP_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);
 
 	/* VSV = very important to remove timers */
 #ifdef CONFIG_SLIP_SMART
@@ -1296,10 +1314,8 @@ static int __init slip_init(void)
 
 	slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev,
 								GFP_KERNEL);
-	if (!slip_devs) {
-		printk(KERN_ERR "SLIP: Can't allocate slip devices array.\n");
+	if (!slip_devs)
 		return -ENOMEM;
-	}
 
 	/* Fill in our line protocol discipline, and register it */
 	status = tty_register_ldisc(N_SLIP, &sl_ldisc);
diff --git a/drivers/net/slip/slip.h b/drivers/net/slip/slip.h
index 67673cf1266..cf32aadf508 100644
--- a/drivers/net/slip/slip.h
+++ b/drivers/net/slip/slip.h
@@ -53,6 +53,7 @@ struct slip {
   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	*/
 
 #ifdef SL_INCLUDE_CSLIP
   struct slcompress	*slcomp;	/* for header compression 	*/