diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/n_tty.c | 88 |
1 files changed, 35 insertions, 53 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index c1c721fa8766..18d72a0258ce 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -108,7 +108,8 @@ struct n_tty_data { /* protected by echo_lock */ unsigned char *echo_buf; - unsigned int echo_pos; + size_t echo_head; + size_t echo_tail; unsigned int echo_cnt; /* protected by output lock */ @@ -135,6 +136,16 @@ static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i) return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; } +static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i) +{ + return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; +} + +static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i) +{ + return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; +} + static inline int tty_put_user(struct tty_struct *tty, unsigned char x, unsigned char __user *ptr) { @@ -325,7 +336,7 @@ 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_pos = ldata->echo_cnt = 0; + ldata->echo_head = ldata->echo_tail = ldata->echo_cnt = 0; mutex_unlock(&ldata->echo_lock); ldata->erasing = 0; @@ -640,8 +651,8 @@ static void process_echoes(struct tty_struct *tty) { struct n_tty_data *ldata = tty->disc_data; int space, nr; + size_t tail; unsigned char c; - unsigned char *cp, *buf_end; if (!ldata->echo_cnt) return; @@ -651,14 +662,12 @@ static void process_echoes(struct tty_struct *tty) space = tty_write_room(tty); - buf_end = ldata->echo_buf + N_TTY_BUF_SIZE; - cp = ldata->echo_buf + ldata->echo_pos; + tail = ldata->echo_tail; nr = ldata->echo_cnt; while (nr > 0) { - c = *cp; + c = echo_buf(ldata, tail); if (c == ECHO_OP_START) { unsigned char op; - unsigned char *opp; int no_space_left = 0; /* @@ -666,18 +675,13 @@ static void process_echoes(struct tty_struct *tty) * operation, get the next byte, which is either the * op code or a control character value. */ - opp = cp + 1; - if (opp == buf_end) - opp -= N_TTY_BUF_SIZE; - op = *opp; + op = echo_buf(ldata, tail + 1); switch (op) { unsigned int num_chars, num_bs; case ECHO_OP_ERASE_TAB: - if (++opp == buf_end) - opp -= N_TTY_BUF_SIZE; - num_chars = *opp; + num_chars = echo_buf(ldata, tail + 2); /* * Determine how many columns to go back @@ -703,20 +707,20 @@ static void process_echoes(struct tty_struct *tty) if (ldata->column > 0) ldata->column--; } - cp += 3; + tail += 3; nr -= 3; break; case ECHO_OP_SET_CANON_COL: ldata->canon_column = ldata->column; - cp += 2; + tail += 2; nr -= 2; break; case ECHO_OP_MOVE_BACK_COL: if (ldata->column > 0) ldata->column--; - cp += 2; + tail += 2; nr -= 2; break; @@ -729,7 +733,7 @@ static void process_echoes(struct tty_struct *tty) tty_put_char(tty, ECHO_OP_START); ldata->column++; space--; - cp += 2; + tail += 2; nr -= 2; break; @@ -751,7 +755,7 @@ static void process_echoes(struct tty_struct *tty) tty_put_char(tty, op ^ 0100); ldata->column += 2; space -= 2; - cp += 2; + tail += 2; nr -= 2; } @@ -769,24 +773,13 @@ static void process_echoes(struct tty_struct *tty) tty_put_char(tty, c); space -= 1; } - cp += 1; + tail += 1; nr -= 1; } - - /* When end of circular buffer reached, wrap around */ - if (cp >= buf_end) - cp -= N_TTY_BUF_SIZE; } - if (nr == 0) { - ldata->echo_pos = 0; - ldata->echo_cnt = 0; - } else { - int num_processed = ldata->echo_cnt - nr; - ldata->echo_pos += num_processed; - ldata->echo_pos &= N_TTY_BUF_SIZE - 1; - ldata->echo_cnt = nr; - } + ldata->echo_tail = tail; + ldata->echo_cnt = nr; mutex_unlock(&ldata->echo_lock); mutex_unlock(&ldata->output_lock); @@ -807,37 +800,26 @@ static void process_echoes(struct tty_struct *tty) static void add_echo_byte(unsigned char c, struct n_tty_data *ldata) { - int new_byte_pos; - if (ldata->echo_cnt == N_TTY_BUF_SIZE) { - /* Circular buffer is already at capacity */ - new_byte_pos = ldata->echo_pos; - + 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 (ldata->echo_buf[ldata->echo_pos] == ECHO_OP_START) { - if (ldata->echo_buf[(ldata->echo_pos + 1) & - (N_TTY_BUF_SIZE - 1)] == - ECHO_OP_ERASE_TAB) { - ldata->echo_pos += 3; + if (echo_buf(ldata, head) == ECHO_OP_START) { + if (echo_buf(ldata, head + 1) == ECHO_OP_ERASE_TAB) { + ldata->echo_tail += 3; ldata->echo_cnt -= 2; } else { - ldata->echo_pos += 2; + ldata->echo_tail += 2; ldata->echo_cnt -= 1; } - } else { - ldata->echo_pos++; - } - ldata->echo_pos &= N_TTY_BUF_SIZE - 1; - } else { - new_byte_pos = ldata->echo_pos + ldata->echo_cnt; - new_byte_pos &= N_TTY_BUF_SIZE - 1; + } else + ldata->echo_tail++; + } else ldata->echo_cnt++; - } - ldata->echo_buf[new_byte_pos] = c; + *echo_buf_addr(ldata, ldata->echo_head++) = c; } /** |