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n_tty: Only flush echo output if actually output

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Don't have the driver flush received echoes if no echoes were
actually output.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2013-06-15 10:04:27 -04:00 committed by Greg Kroah-Hartman
parent cbfd0340ae
commit bc5b1ec586
1 changed files with 10 additions and 8 deletions
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18
drivers/tty/n_tty.c
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@ -646,14 +646,14 @@ break_out:
* Locking: callers must hold output_lock
*/
static void __process_echoes(struct tty_struct *tty)
static size_t __process_echoes(struct tty_struct *tty)
{
struct n_tty_data *ldata = tty->disc_data;
int space, nr;
int space, old_space;
size_t tail;
unsigned char c;
space = tty_write_room(tty);
old_space = space = tty_write_room(tty);
tail = ldata->echo_tail;
nr = ldata->echo_commit - ldata->echo_tail;
@ -785,12 +785,13 @@ static void __process_echoes(struct tty_struct *tty)
}
ldata->echo_tail = tail;
return old_space - space;
}
static void commit_echoes(struct tty_struct *tty)
{
struct n_tty_data *ldata = tty->disc_data;
size_t nr, old;
size_t nr, old, echoed;
size_t head;
head = ldata->echo_head;
@ -805,25 +806,26 @@ static void commit_echoes(struct tty_struct *tty)
mutex_lock(&ldata->output_lock);
ldata->echo_commit = head;
__process_echoes(tty);
echoed = __process_echoes(tty);
mutex_unlock(&ldata->output_lock);
if (tty->ops->flush_chars)
if (echoed && tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}
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)
return;
mutex_lock(&ldata->output_lock);
__process_echoes(tty);
echoed = __process_echoes(tty);
mutex_unlock(&ldata->output_lock);
if (tty->ops->flush_chars)
if (echoed && tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}