diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2013-06-15 13:14:22 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-07-23 23:43:00 (GMT) |
| commit | a2f73be8ee36e48f11f89ab705beb3c587a2f320 (patch) | |
| tree | 1612dd60ae378dfb1369001c2eed60265797f1c0 /drivers/tty | |
| parent | bc5a5e3f45d047844830233fb95b19a95c864a0f (diff) | |
| download | linux-fsl-qoriq-a2f73be8ee36e48f11f89ab705beb3c587a2f320.tar.xz | |
n_tty: Remove read_cnt
Storing the read_cnt creates an unnecessary shared variable
between the single-producer (n_tty_receive_buf()) and the
single-consumer (n_tty_read()).
Compute read_cnt from head & tail instead of storing.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/n_tty.c | 15 |
1 files changed, 2 insertions, 13 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index b2fef10..d159059 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -98,7 +98,6 @@ struct n_tty_data { char *read_buf; size_t read_head; size_t read_tail; - int read_cnt; int minimum_to_wake; unsigned char *echo_buf; @@ -117,7 +116,7 @@ struct n_tty_data { static inline size_t read_cnt(struct n_tty_data *ldata) { - return ldata->read_cnt; + return ldata->read_head - ldata->read_tail; } static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i) @@ -198,7 +197,6 @@ static void put_tty_queue_nolock(unsigned char c, struct n_tty_data *ldata) if (read_cnt(ldata) < N_TTY_BUF_SIZE) { *read_buf_addr(ldata, ldata->read_head) = c; ldata->read_head++; - ldata->read_cnt++; } } @@ -239,7 +237,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata) unsigned long flags; raw_spin_lock_irqsave(&ldata->read_lock, flags); - ldata->read_head = ldata->read_tail = ldata->read_cnt = 0; + ldata->read_head = ldata->read_tail = 0; raw_spin_unlock_irqrestore(&ldata->read_lock, flags); mutex_lock(&ldata->echo_lock); @@ -942,16 +940,12 @@ static void eraser(unsigned char c, struct tty_struct *tty) else { if (!L_ECHO(tty)) { raw_spin_lock_irqsave(&ldata->read_lock, flags); - ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) & - (N_TTY_BUF_SIZE - 1)); ldata->read_head = ldata->canon_head; raw_spin_unlock_irqrestore(&ldata->read_lock, flags); return; } if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { raw_spin_lock_irqsave(&ldata->read_lock, flags); - ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) & - (N_TTY_BUF_SIZE - 1)); ldata->read_head = ldata->canon_head; raw_spin_unlock_irqrestore(&ldata->read_lock, flags); finish_erasing(ldata); @@ -989,7 +983,6 @@ static void eraser(unsigned char c, struct tty_struct *tty) cnt = ldata->read_head - head; raw_spin_lock_irqsave(&ldata->read_lock, flags); ldata->read_head = head; - ldata->read_cnt -= cnt; raw_spin_unlock_irqrestore(&ldata->read_lock, flags); if (L_ECHO(tty)) { if (L_ECHOPRT(tty)) { @@ -1448,7 +1441,6 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, i = min(count, i); memcpy(read_buf_addr(ldata, ldata->read_head), cp, i); ldata->read_head += i; - ldata->read_cnt += i; cp += i; count -= i; @@ -1457,7 +1449,6 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, i = min(count, i); memcpy(read_buf_addr(ldata, ldata->read_head), cp, i); ldata->read_head += i; - ldata->read_cnt += i; raw_spin_unlock_irqrestore(&ldata->read_lock, cpuflags); } else { for (i = count, p = cp, f = fp; i; i--, p++) { @@ -1762,7 +1753,6 @@ static int copy_from_read_buf(struct tty_struct *tty, ldata->icanon); raw_spin_lock_irqsave(&ldata->read_lock, flags); ldata->read_tail += n; - ldata->read_cnt -= n; /* Turn single EOF into zero-length read */ if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata)) n = 0; @@ -1850,7 +1840,6 @@ static int canon_copy_from_read_buf(struct tty_struct *tty, raw_spin_lock_irqsave(&ldata->read_lock, flags); ldata->read_tail += c; - ldata->read_cnt -= c; if (found) { __clear_bit(eol, ldata->read_flags); /* this test should be redundant: |