[PATCH 16/20] n_tty: Factor PARMRK from normal per-char i/o

From: Peter Hurley
Date: Mon Apr 15 2013 - 12:03:53 EST


Handle PARMRK processing on the slow per-char i/o path.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 6316426..e26a3bf 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1457,6 +1457,47 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
}

static inline void
+n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+
+ /*
+ * If the previous character was LNEXT, or we know that this
+ * character is not one of the characters that we'll have to
+ * handle specially, do shortcut processing to speed things
+ * up.
+ */
+ if (!test_bit(c, ldata->char_map) || ldata->lnext) {
+ ldata->lnext = 0;
+
+ if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
+ I_IXANY(tty)) {
+ start_tty(tty);
+ process_echoes(tty);
+ }
+
+ if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - 1)) {
+ /* beep if no space */
+ if (L_ECHO(tty))
+ process_output('\a', tty);
+ return;
+ }
+ if (L_ECHO(tty)) {
+ finish_erasing(ldata);
+ /* Record the column of first canon char. */
+ if (ldata->canon_head == ldata->read_head)
+ echo_set_canon_col(ldata);
+ echo_char(c, tty);
+ commit_echoes(tty);
+ }
+ put_tty_queue(c, ldata);
+ return;
+ }
+
+ n_tty_receive_char_special(tty, c);
+}
+
+static inline void
n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
{
if (I_ISTRIP(tty))
@@ -1608,7 +1649,7 @@ n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
if (fp)
flag = *fp++;
if (likely(flag == TTY_NORMAL))
- n_tty_receive_char(tty, *cp++);
+ n_tty_receive_char_fast(tty, *cp++);
else
n_tty_receive_char_flagged(tty, *cp++, flag);
}
@@ -1627,7 +1668,7 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
else if (tty->closing && !L_EXTPROC(tty))
n_tty_receive_buf_closing(tty, cp, fp, count);
else {
- if (!preops)
+ if (!preops && !I_PARMRK(tty))
n_tty_receive_buf_fast(tty, cp, fp, count);
else
n_tty_receive_buf_standard(tty, cp, fp, count);
--
1.8.1.2

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