1 files changed, 19 insertions, 8 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 7cdd1eb9406c..34aacaaae14a 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -93,6 +93,7 @@ struct n_tty_data {
         size_t canon_head;
         size_t echo_head;
         size_t echo_commit;
+        size_t echo_mark;
         DECLARE_BITMAP(char_map, 256);
 
         /* private to n_tty_receive_overrun (single-threaded) */
@@ -336,6 +337,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
 {
         ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
         ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
+        ldata->echo_mark = 0;
         ldata->line_start = 0;
 
         ldata->erasing = 0;
@@ -768,7 +770,7 @@ static size_t __process_echoes(struct tty_struct *tty)
          * data at the tail to prevent a subsequent overrun */
         while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
                 if (echo_buf(ldata, tail) == ECHO_OP_START) {
-                        if (echo_buf(ldata, tail) == ECHO_OP_ERASE_TAB)
+                        if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
                                 tail += 3;
                         else
                                 tail += 2;
@@ -787,6 +789,7 @@ static void commit_echoes(struct tty_struct *tty)
         size_t head;
 
         head = ldata->echo_head;
+        ldata->echo_mark = head;
         old = ldata->echo_commit - ldata->echo_tail;
 
         /* Process committed echoes if the accumulated # of bytes
@@ -810,10 +813,12 @@ static void process_echoes(struct tty_struct *tty)
         struct n_tty_data *ldata = tty->disc_data;
         size_t echoed;
 
-        if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_tail)
+        if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
+            ldata->echo_mark == ldata->echo_tail)
                 return;
 
         mutex_lock(&ldata->output_lock);
+        ldata->echo_commit = ldata->echo_mark;
         echoed = __process_echoes(tty);
         mutex_unlock(&ldata->output_lock);
 
@@ -821,11 +826,13 @@ static void process_echoes(struct tty_struct *tty)
                 tty->ops->flush_chars(tty);
 }
 
+/* NB: echo_mark and echo_head should be equivalent here */
 static void flush_echoes(struct tty_struct *tty)
 {
         struct n_tty_data *ldata = tty->disc_data;
 
-        if (!L_ECHO(tty) || ldata->echo_commit == ldata->echo_head)
+        if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||
+            ldata->echo_commit == ldata->echo_head)
                 return;
 
         mutex_lock(&ldata->output_lock);
@@ -1998,7 +2005,10 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
                 found = 1;
 
         size = N_TTY_BUF_SIZE - tail;
-        n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
+        n = eol - tail;
+        if (n > 4096)
+                n += 4096;
+        n += found;
         c = n;
 
         if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
@@ -2243,18 +2253,19 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
                 if (time)
                         timeout = time;
         }
-        mutex_unlock(&ldata->atomic_read_lock);
-        remove_wait_queue(&tty->read_wait, &wait);
+        n_tty_set_room(tty);
+        up_read(&tty->termios_rwsem);
 
+        remove_wait_queue(&tty->read_wait, &wait);
         if (!waitqueue_active(&tty->read_wait))
                 ldata->minimum_to_wake = minimum;
 
+        mutex_unlock(&ldata->atomic_read_lock);
+
         __set_current_state(TASK_RUNNING);
         if (b - buf)
                 retval = b - buf;
 
-        n_tty_set_room(tty);
-        up_read(&tty->termios_rwsem);
         return retval;
 }