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>
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@ -98,7 +98,6 @@ struct n_tty_data {
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char *read_buf;
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char *read_buf;
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size_t read_head;
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size_t read_head;
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size_t read_tail;
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size_t read_tail;
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int read_cnt;
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int minimum_to_wake;
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int minimum_to_wake;
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unsigned char *echo_buf;
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unsigned char *echo_buf;
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@ -117,7 +116,7 @@ struct n_tty_data {
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static inline size_t read_cnt(struct n_tty_data *ldata)
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static inline size_t read_cnt(struct n_tty_data *ldata)
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{
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{
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return ldata->read_cnt;
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return ldata->read_head - ldata->read_tail;
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}
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}
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static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
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static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i)
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@ -198,7 +197,6 @@ static void put_tty_queue_nolock(unsigned char c, struct n_tty_data *ldata)
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if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
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if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
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*read_buf_addr(ldata, ldata->read_head) = c;
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*read_buf_addr(ldata, ldata->read_head) = c;
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ldata->read_head++;
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ldata->read_head++;
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ldata->read_cnt++;
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}
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}
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}
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}
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@ -239,7 +237,7 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
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unsigned long flags;
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unsigned long flags;
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_head = ldata->read_tail = ldata->read_cnt = 0;
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ldata->read_head = ldata->read_tail = 0;
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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mutex_lock(&ldata->echo_lock);
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mutex_lock(&ldata->echo_lock);
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@ -942,16 +940,12 @@ static void eraser(unsigned char c, struct tty_struct *tty)
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else {
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else {
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if (!L_ECHO(tty)) {
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if (!L_ECHO(tty)) {
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) &
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(N_TTY_BUF_SIZE - 1));
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ldata->read_head = ldata->canon_head;
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ldata->read_head = ldata->canon_head;
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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return;
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return;
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}
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}
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if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
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if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) {
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_cnt -= ((ldata->read_head - ldata->canon_head) &
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(N_TTY_BUF_SIZE - 1));
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ldata->read_head = ldata->canon_head;
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ldata->read_head = ldata->canon_head;
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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finish_erasing(ldata);
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finish_erasing(ldata);
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@ -989,7 +983,6 @@ static void eraser(unsigned char c, struct tty_struct *tty)
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cnt = ldata->read_head - head;
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cnt = ldata->read_head - head;
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_head = head;
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ldata->read_head = head;
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ldata->read_cnt -= cnt;
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
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if (L_ECHO(tty)) {
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if (L_ECHO(tty)) {
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if (L_ECHOPRT(tty)) {
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if (L_ECHOPRT(tty)) {
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@ -1448,7 +1441,6 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
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i = min(count, i);
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i = min(count, i);
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memcpy(read_buf_addr(ldata, ldata->read_head), cp, i);
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memcpy(read_buf_addr(ldata, ldata->read_head), cp, i);
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ldata->read_head += i;
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ldata->read_head += i;
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ldata->read_cnt += i;
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cp += i;
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cp += i;
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count -= i;
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count -= i;
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@ -1457,7 +1449,6 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
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i = min(count, i);
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i = min(count, i);
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memcpy(read_buf_addr(ldata, ldata->read_head), cp, i);
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memcpy(read_buf_addr(ldata, ldata->read_head), cp, i);
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ldata->read_head += i;
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ldata->read_head += i;
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ldata->read_cnt += i;
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raw_spin_unlock_irqrestore(&ldata->read_lock, cpuflags);
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raw_spin_unlock_irqrestore(&ldata->read_lock, cpuflags);
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} else {
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} else {
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for (i = count, p = cp, f = fp; i; i--, p++) {
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for (i = count, p = cp, f = fp; i; i--, p++) {
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@ -1762,7 +1753,6 @@ static int copy_from_read_buf(struct tty_struct *tty,
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ldata->icanon);
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ldata->icanon);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_tail += n;
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ldata->read_tail += n;
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ldata->read_cnt -= n;
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/* Turn single EOF into zero-length read */
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/* Turn single EOF into zero-length read */
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if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
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if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
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n = 0;
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n = 0;
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@ -1850,7 +1840,6 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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raw_spin_lock_irqsave(&ldata->read_lock, flags);
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ldata->read_tail += c;
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ldata->read_tail += c;
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ldata->read_cnt -= c;
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if (found) {
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if (found) {
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__clear_bit(eol, ldata->read_flags);
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__clear_bit(eol, ldata->read_flags);
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/* this test should be redundant:
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/* this test should be redundant:
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