diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2013-06-15 10:04:23 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-07-23 17:02:21 -0700 |
| commit | 862eeffef1b465a12412f4ae6e5987ae292c968d (patch) | |
| tree | 4fc9ae42e841d6402906a12bf1dbd1594c179b3a | |
| parent | addaebccf63a8c9f7c7a62ce1ceb9da4307c5a1c (diff) | |
n_tty: Replace echo_cnt with computed value
Prepare for lockless echo_buf handling; compute current byte count
of echo_buf from head and tail indices.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/tty/n_tty.c | 20 |
1 files changed, 7 insertions, 13 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 18d72a0258ce..8406a23ee920 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -110,7 +110,6 @@ struct n_tty_data { unsigned char *echo_buf; size_t echo_head; size_t echo_tail; - unsigned int echo_cnt; /* protected by output lock */ unsigned int column; @@ -336,7 +335,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata) ldata->read_head = ldata->canon_head = ldata->read_tail = 0; mutex_lock(&ldata->echo_lock); - ldata->echo_head = ldata->echo_tail = ldata->echo_cnt = 0; + ldata->echo_head = ldata->echo_tail = 0; mutex_unlock(&ldata->echo_lock); ldata->erasing = 0; @@ -654,7 +653,7 @@ static void process_echoes(struct tty_struct *tty) size_t tail; unsigned char c; - if (!ldata->echo_cnt) + if (ldata->echo_head == ldata->echo_tail) return; mutex_lock(&ldata->output_lock); @@ -663,7 +662,7 @@ static void process_echoes(struct tty_struct *tty) space = tty_write_room(tty); tail = ldata->echo_tail; - nr = ldata->echo_cnt; + nr = ldata->echo_head - ldata->echo_tail; while (nr > 0) { c = echo_buf(ldata, tail); if (c == ECHO_OP_START) { @@ -779,7 +778,6 @@ static void process_echoes(struct tty_struct *tty) } ldata->echo_tail = tail; - ldata->echo_cnt = nr; mutex_unlock(&ldata->echo_lock); mutex_unlock(&ldata->output_lock); @@ -800,24 +798,20 @@ static void process_echoes(struct tty_struct *tty) static void add_echo_byte(unsigned char c, struct n_tty_data *ldata) { - if (ldata->echo_cnt == N_TTY_BUF_SIZE) { + if (ldata->echo_head - ldata->echo_tail == N_TTY_BUF_SIZE) { size_t head = ldata->echo_head; /* * Since the buffer start position needs to be advanced, * be sure to step by a whole operation byte group. */ if (echo_buf(ldata, head) == ECHO_OP_START) { - if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) { + if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) ldata->echo_tail += 3; - ldata->echo_cnt -= 2; - } else { + else ldata->echo_tail += 2; - ldata->echo_cnt -= 1; - } } else ldata->echo_tail++; - } else - ldata->echo_cnt++; + } *echo_buf_addr(ldata, ldata->echo_head++) = c; } |