n_tty: Split n_tty_chars_in_buffer() for reader-only interface
N_TTY .chars_in_buffer() method requires serialized access if
the current thread is not the single-consumer, n_tty_read().
Separate the internal interface; prepare for lockless read-side.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 74dcedd..594a3c1 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -277,7 +277,7 @@
* Locking: read_lock
*/
-static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
+static ssize_t chars_in_buffer(struct tty_struct *tty)
{
struct n_tty_data *ldata = tty->disc_data;
unsigned long flags;
@@ -295,6 +295,11 @@
return n;
}
+static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty)
+{
+ return chars_in_buffer(tty);
+}
+
/**
* is_utf8_continuation - utf8 multibyte check
* @c: byte to check
@@ -2032,7 +2037,7 @@
}
/* If there is enough space in the read buffer now, let the
- * low-level driver know. We use n_tty_chars_in_buffer() to
+ * low-level driver know. We use chars_in_buffer() to
* check the buffer, as it now knows about canonical mode.
* Otherwise, if the driver is throttled and the line is
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
@@ -2040,7 +2045,7 @@
*/
while (1) {
tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
- if (n_tty_chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
+ if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
break;
if (!tty->count)
break;