tty: make receive_buf() return the amout of bytes received

it makes it simpler to keep track of the amount of
bytes received and simplifies how flush_to_ldisc counts
the remaining bytes. It also fixes a bug of lost bytes
on n_tty when flushing too many bytes via the USB
serial gadget driver.

Tested-by: Stefan Bigler <stefan.bigler@keymile.com>
Tested-by: Toby Gray <toby.gray@realvnc.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

9 files changed, 51 insertions, 29 deletions

diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c
index 3df0c0f8b8bf..73c7e03617ec 100644
--- a/drivers/net/caif/caif_serial.c
+++ b/drivers/net/caif/caif_serial.c
@@ -167,8 +167,8 @@ static inline void debugfs_tx(struct ser_device *ser, const u8 *data, int size)
 
 #endif
 
-static void ldisc_receive(struct tty_struct *tty, const u8 *data,
-                        char *flags, int count)
+static unsigned int ldisc_receive(struct tty_struct *tty,
+                const u8 *data, char *flags, int count)
 {
         struct sk_buff *skb = NULL;
         struct ser_device *ser;
@@ -215,6 +215,8 @@ static void ldisc_receive(struct tty_struct *tty, const u8 *data,
         } else
                 ++ser->dev->stats.rx_dropped;
         update_tty_status(ser);
+
+        return count;
 }
 
 static int handle_tx(struct ser_device *ser)
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index b423965a78d1..c600954998d5 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -425,16 +425,17 @@ static void slc_setup(struct net_device *dev)
  * in parallel
  */
 
-static void slcan_receive_buf(struct tty_struct *tty,
+static unsigned int slcan_receive_buf(struct tty_struct *tty,
                               const unsigned char *cp, char *fp, int count)
 {
         struct slcan *sl = (struct slcan *) tty->disc_data;
+        int bytes = count;
 
         if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
-                return;
+                return -ENODEV;
 
         /* Read the characters out of the buffer */
-        while (count--) {
+        while (bytes--) {
                 if (fp && *fp++) {
                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
                                 sl->dev->stats.rx_errors++;
@@ -443,6 +444,8 @@ static void slcan_receive_buf(struct tty_struct *tty,
                 }
                 slcan_unesc(sl, *cp++);
         }
+
+        return count;
 }
 
 /************************************
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index 3e5d0b6b6516..992089639ea4 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -456,7 +456,7 @@ out:
  * a block of 6pack data has been received, which can now be decapsulated
  * and sent on to some IP layer for further processing.
  */
-static void sixpack_receive_buf(struct tty_struct *tty,
+static unsigned int sixpack_receive_buf(struct tty_struct *tty,
         const unsigned char *cp, char *fp, int count)
 {
         struct sixpack *sp;
@@ -464,11 +464,11 @@ static void sixpack_receive_buf(struct tty_struct *tty,
         int count1;
 
         if (!count)
-                return;
+                return 0;
 
         sp = sp_get(tty);
         if (!sp)
-                return;
+                return -ENODEV;
 
         memcpy(buf, cp, count < sizeof(buf) ? count : sizeof(buf));
 
@@ -487,6 +487,8 @@ static void sixpack_receive_buf(struct tty_struct *tty,
 
         sp_put(sp);
         tty_unthrottle(tty);
+
+        return count1;
 }
 
 /*
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 4c628393c8b1..0e4f23531140 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -923,13 +923,14 @@ static long mkiss_compat_ioctl(struct tty_struct *tty, struct file *file,
  * a block of data has been received, which can now be decapsulated
  * and sent on to the AX.25 layer for further processing.
  */
-static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-        char *fp, int count)
+static unsigned int mkiss_receive_buf(struct tty_struct *tty,
+                const unsigned char *cp, char *fp, int count)
 {
         struct mkiss *ax = mkiss_get(tty);
+        int bytes = count;
 
         if (!ax)
-                return;
+                return -ENODEV;
 
         /*
          * Argh! mtu change time! - costs us the packet part received
@@ -939,7 +940,7 @@ static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                 ax_changedmtu(ax);
 
         /* Read the characters out of the buffer */
-        while (count--) {
+        while (bytes--) {
                 if (fp != NULL && *fp++) {
                         if (!test_and_set_bit(AXF_ERROR, &ax->flags))
                                 ax->dev->stats.rx_errors++;
@@ -952,6 +953,8 @@ static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 
         mkiss_put(ax);
         tty_unthrottle(tty);
+
+        return count;
 }
 
 /*
diff --git a/drivers/net/irda/irtty-sir.c b/drivers/net/irda/irtty-sir.c
index 3352b2443e58..035861d8acb1 100644
--- a/drivers/net/irda/irtty-sir.c
+++ b/drivers/net/irda/irtty-sir.c
@@ -216,23 +216,23 @@ static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t
  * usbserial:   urb-complete-interrupt / softint
  */
 
-static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-                              char *fp, int count) 
+static unsigned int irtty_receive_buf(struct tty_struct *tty,
+                const unsigned char *cp, char *fp, int count)
 {
         struct sir_dev *dev;
         struct sirtty_cb *priv = tty->disc_data;
         int     i;
 
-        IRDA_ASSERT(priv != NULL, return;);
-        IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
+        IRDA_ASSERT(priv != NULL, return -ENODEV;);
+        IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -EINVAL;);
 
         if (unlikely(count==0))         /* yes, this happens */
-                return;
+                return 0;
 
         dev = priv->dev;
         if (!dev) {
                 IRDA_WARNING("%s(), not ready yet!\n", __func__);
-                return;
+                return -ENODEV;
         }
 
         for (i = 0; i < count; i++) {
@@ -242,11 +242,13 @@ static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                 if (fp && *fp++) { 
                         IRDA_DEBUG(0, "Framing or parity error!\n");
                         sirdev_receive(dev, NULL, 0);   /* notify sir_dev (updating stats) */
-                        return;
+                        return -EINVAL;
                 }
         }
 
         sirdev_receive(dev, cp, count);
+
+        return count;
 }
 
 /*
diff --git a/drivers/net/ppp_async.c b/drivers/net/ppp_async.c
index a1b82c9c67d2..53872d7d7382 100644
--- a/drivers/net/ppp_async.c
+++ b/drivers/net/ppp_async.c
@@ -340,7 +340,7 @@ ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 }
 
 /* May sleep, don't call from interrupt level or with interrupts disabled */
-static void
+static unsigned int
 ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
                   char *cflags, int count)
 {
@@ -348,7 +348,7 @@ ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
         unsigned long flags;
 
         if (!ap)
-                return;
+                return -ENODEV;
         spin_lock_irqsave(&ap->recv_lock, flags);
         ppp_async_input(ap, buf, cflags, count);
         spin_unlock_irqrestore(&ap->recv_lock, flags);
@@ -356,6 +356,8 @@ ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
                 tasklet_schedule(&ap->tsk);
         ap_put(ap);
         tty_unthrottle(tty);
+
+        return count;
 }
 
 static void
diff --git a/drivers/net/ppp_synctty.c b/drivers/net/ppp_synctty.c
index 2573f525f11c..0815790a5cf9 100644
--- a/drivers/net/ppp_synctty.c
+++ b/drivers/net/ppp_synctty.c
@@ -381,7 +381,7 @@ ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
 }
 
 /* May sleep, don't call from interrupt level or with interrupts disabled */
-static void
+static unsigned int
 ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
                   char *cflags, int count)
 {
@@ -389,7 +389,7 @@ ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
         unsigned long flags;
 
         if (!ap)
-                return;
+                return -ENODEV;
         spin_lock_irqsave(&ap->recv_lock, flags);
         ppp_sync_input(ap, buf, cflags, count);
         spin_unlock_irqrestore(&ap->recv_lock, flags);
@@ -397,6 +397,8 @@ ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
                 tasklet_schedule(&ap->tsk);
         sp_put(ap);
         tty_unthrottle(tty);
+
+        return count;
 }
 
 static void
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 86cbb9ea2f26..86718d358395 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -670,16 +670,17 @@ static void sl_setup(struct net_device *dev)
  * in parallel
  */
 
-static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
-                                                        char *fp, int count)
+static unsigned int slip_receive_buf(struct tty_struct *tty,
+                const unsigned char *cp, char *fp, int count)
 {
         struct slip *sl = tty->disc_data;
+        int bytes = count;
 
         if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
-                return;
+                return -ENODEV;
 
         /* Read the characters out of the buffer */
-        while (count--) {
+        while (bytes--) {
                 if (fp && *fp++) {
                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
                                 sl->dev->stats.rx_errors++;
@@ -693,6 +694,8 @@ static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 #endif
                         slip_unesc(sl, *cp++);
         }
+
+        return count;
 }
 
 /************************************
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 24297b274cd4..40398bf7d036 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -517,17 +517,18 @@ static int x25_asy_close(struct net_device *dev)
  * and sent on to some IP layer for further processing.
  */
 
-static void x25_asy_receive_buf(struct tty_struct *tty,
+static unsigned int x25_asy_receive_buf(struct tty_struct *tty,
                                 const unsigned char *cp, char *fp, int count)
 {
         struct x25_asy *sl = tty->disc_data;
+        int bytes = count;
 
         if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
                 return;
 
 
         /* Read the characters out of the buffer */
-        while (count--) {
+        while (bytes--) {
                 if (fp && *fp++) {
                         if (!test_and_set_bit(SLF_ERROR, &sl->flags))
                                 sl->dev->stats.rx_errors++;
@@ -536,6 +537,8 @@ static void x25_asy_receive_buf(struct tty_struct *tty,
                 }
                 x25_asy_unesc(sl, *cp++);
         }
+
+        return count;
 }
 
 /*