struct n_tty_data {
/* producer-published */
size_t read_head;
+ size_t commit_head;
size_t canon_head;
size_t echo_head;
size_t echo_commit;
return put_user(x, ptr);
}
-static int receive_room(struct tty_struct *tty)
-{
- struct n_tty_data *ldata = tty->disc_data;
- int left;
-
- if (I_PARMRK(tty)) {
- /* Multiply read_cnt by 3, since each byte might take up to
- * three times as many spaces when PARMRK is set (depending on
- * its flags, e.g. parity error). */
- left = N_TTY_BUF_SIZE - read_cnt(ldata) * 3 - 1;
- } else
- left = N_TTY_BUF_SIZE - read_cnt(ldata) - 1;
-
- /*
- * If we are doing input canonicalization, and there are no
- * pending newlines, let characters through without limit, so
- * that erase characters will be handled. Other excess
- * characters will be beeped.
- */
- if (left <= 0)
- left = ldata->icanon && ldata->canon_head == ldata->read_tail;
-
- return left;
-}
-
/**
- * n_tty_set_room - receive space
+ * n_tty_kick_worker - start input worker (if required)
* @tty: terminal
*
- * Re-schedules the flip buffer work if space just became available.
+ * Re-schedules the flip buffer work if it may have stopped
*
* Caller holds exclusive termios_rwsem
* or
* holds non-exclusive termios_rwsem
*/
-static void n_tty_set_room(struct tty_struct *tty)
+static void n_tty_kick_worker(struct tty_struct *tty)
{
struct n_tty_data *ldata = tty->disc_data;
- /* Did this open up the receive buffer? We may need to flip */
- if (unlikely(ldata->no_room) && receive_room(tty)) {
+ /* Did the input worker stop? Restart it */
+ if (unlikely(ldata->no_room)) {
ldata->no_room = 0;
WARN_RATELIMIT(tty->port->itty == NULL,
ssize_t n = 0;
if (!ldata->icanon)
- n = read_cnt(ldata);
+ n = ldata->commit_head - ldata->read_tail;
else
n = ldata->canon_head - ldata->read_tail;
return n;
static void n_tty_check_throttle(struct tty_struct *tty)
{
- if (tty->driver->type == TTY_DRIVER_TYPE_PTY)
- return;
+ struct n_tty_data *ldata = tty->disc_data;
+
/*
* Check the remaining room for the input canonicalization
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
+ if (ldata->icanon && ldata->canon_head == ldata->read_tail)
+ return;
+
while (1) {
int throttled;
tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
- if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
+ if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE)
break;
throttled = tty_throttle_safe(tty);
if (!throttled)
return;
if (!tty->count)
return;
- n_tty_set_room(tty);
+ n_tty_kick_worker(tty);
n_tty_write_wakeup(tty->link);
if (waitqueue_active(&tty->link->write_wait))
wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
break;
if (!tty->count)
break;
- n_tty_set_room(tty);
+ n_tty_kick_worker(tty);
unthrottled = tty_unthrottle_safe(tty);
if (!unthrottled)
break;
*
* n_tty_receive_buf()/producer path:
* caller holds non-exclusive termios_rwsem
- * modifies read_head
- *
- * read_head is only considered 'published' if canonical mode is
- * not active.
*/
static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
{
ldata->read_head = ldata->canon_head = ldata->read_tail = 0;
ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0;
+ ldata->commit_head = 0;
ldata->echo_mark = 0;
ldata->line_start = 0;
{
down_write(&tty->termios_rwsem);
reset_buffer_flags(tty->disc_data);
- n_tty_set_room(tty);
+ n_tty_kick_worker(tty);
if (tty->link)
n_tty_packet_mode_flush(tty);
*
* n_tty_receive_buf()/producer path:
* caller holds non-exclusive termios_rwsem
- * modifies read_head
- *
- * Modifying the read_head is not considered a publish in this context
- * because canonical mode is active -- only canon_head publishes
*/
static void eraser(unsigned char c, struct tty_struct *tty)
* Called when a signal is being sent due to terminal input.
* Called from the driver receive_buf path so serialized.
*
+ * Performs input and output flush if !NOFLSH. In this context, the echo
+ * buffer is 'output'. The signal is processed first to alert any current
+ * readers or writers to discontinue and exit their i/o loops.
+ *
* Locking: ctrl_lock
*/
static void isig(int sig, struct tty_struct *tty)
{
+ struct n_tty_data *ldata = tty->disc_data;
struct pid *tty_pgrp = tty_get_pgrp(tty);
if (tty_pgrp) {
kill_pgrp(tty_pgrp, sig, 1);
put_pid(tty_pgrp);
}
+
+ if (!L_NOFLSH(tty)) {
+ up_read(&tty->termios_rwsem);
+ down_write(&tty->termios_rwsem);
+
+ /* clear echo buffer */
+ mutex_lock(&ldata->output_lock);
+ ldata->echo_head = ldata->echo_tail = 0;
+ ldata->echo_mark = ldata->echo_commit = 0;
+ mutex_unlock(&ldata->output_lock);
+
+ /* clear output buffer */
+ tty_driver_flush_buffer(tty);
+
+ /* clear input buffer */
+ reset_buffer_flags(tty->disc_data);
+
+ /* notify pty master of flush */
+ if (tty->link)
+ n_tty_packet_mode_flush(tty);
+
+ up_write(&tty->termios_rwsem);
+ down_read(&tty->termios_rwsem);
+ }
}
/**
*
* n_tty_receive_buf()/producer path:
* caller holds non-exclusive termios_rwsem
- * publishes read_head via put_tty_queue()
*
* Note: may get exclusive termios_rwsem if flushing input buffer
*/
return;
if (I_BRKINT(tty)) {
isig(SIGINT, tty);
- if (!L_NOFLSH(tty)) {
- /* flushing needs exclusive termios_rwsem */
- up_read(&tty->termios_rwsem);
- n_tty_flush_buffer(tty);
- tty_driver_flush_buffer(tty);
- down_read(&tty->termios_rwsem);
- }
return;
}
if (I_PARMRK(tty)) {
*
* n_tty_receive_buf()/producer path:
* caller holds non-exclusive termios_rwsem
- * publishes read_head via put_tty_queue()
*/
static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c)
{
static void
n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
{
- if (!L_NOFLSH(tty)) {
- /* flushing needs exclusive termios_rwsem */
- up_read(&tty->termios_rwsem);
- n_tty_flush_buffer(tty);
- tty_driver_flush_buffer(tty);
- down_read(&tty->termios_rwsem);
- }
+ isig(signal, tty);
if (I_IXON(tty))
start_tty(tty);
if (L_ECHO(tty)) {
commit_echoes(tty);
} else
process_echoes(tty);
- isig(signal, tty);
return;
}
* n_tty_receive_buf()/producer path:
* caller holds non-exclusive termios_rwsem
* publishes canon_head if canonical mode is active
- * otherwise, publishes read_head via put_tty_queue()
*
* Returns 1 if LNEXT was received, else returns 0
*/
handle_newline:
set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags);
put_tty_queue(c, ldata);
- ldata->canon_head = ldata->read_head;
+ smp_store_release(&ldata->canon_head, ldata->read_head);
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
wake_up_interruptible_poll(&tty->read_wait, POLLIN);
n_tty_receive_char_flagged(tty, c, flag);
}
-/**
- * n_tty_receive_buf - data receive
- * @tty: terminal device
- * @cp: buffer
- * @fp: flag buffer
- * @count: characters
- *
- * Called by the terminal driver when a block of characters has
- * been received. This function must be called from soft contexts
- * not from interrupt context. The driver is responsible for making
- * calls one at a time and in order (or using flush_to_ldisc)
- *
- * n_tty_receive_buf()/producer path:
- * claims non-exclusive termios_rwsem
- * publishes read_head and canon_head
- */
-
static void
n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
size_t n, head;
head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
- n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
- n = min_t(size_t, count, n);
+ n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
memcpy(read_buf_addr(ldata, head), cp, n);
ldata->read_head += n;
cp += n;
count -= n;
head = ldata->read_head & (N_TTY_BUF_SIZE - 1);
- n = N_TTY_BUF_SIZE - max(read_cnt(ldata), head);
- n = min_t(size_t, count, n);
+ n = min_t(size_t, count, N_TTY_BUF_SIZE - head);
memcpy(read_buf_addr(ldata, head), cp, n);
ldata->read_head += n;
}
tty->ops->flush_chars(tty);
}
- if ((!ldata->icanon && (read_cnt(ldata) >= ldata->minimum_to_wake)) ||
- L_EXTPROC(tty)) {
+ if (ldata->icanon && !L_EXTPROC(tty))
+ return;
+
+ /* publish read_head to consumer */
+ smp_store_release(&ldata->commit_head, ldata->read_head);
+
+ if ((read_cnt(ldata) >= ldata->minimum_to_wake) || L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
wake_up_interruptible_poll(&tty->read_wait, POLLIN);
}
}
+/**
+ * n_tty_receive_buf_common - process input
+ * @tty: device to receive input
+ * @cp: input chars
+ * @fp: flags for each char (if NULL, all chars are TTY_NORMAL)
+ * @count: number of input chars in @cp
+ *
+ * Called by the terminal driver when a block of characters has
+ * been received. This function must be called from soft contexts
+ * not from interrupt context. The driver is responsible for making
+ * calls one at a time and in order (or using flush_to_ldisc)
+ *
+ * Returns the # of input chars from @cp which were processed.
+ *
+ * In canonical mode, the maximum line length is 4096 chars (including
+ * the line termination char); lines longer than 4096 chars are
+ * truncated. After 4095 chars, input data is still processed but
+ * not stored. Overflow processing ensures the tty can always
+ * receive more input until at least one line can be read.
+ *
+ * In non-canonical mode, the read buffer will only accept 4095 chars;
+ * this provides the necessary space for a newline char if the input
+ * mode is switched to canonical.
+ *
+ * Note it is possible for the read buffer to _contain_ 4096 chars
+ * in non-canonical mode: the read buffer could already contain the
+ * maximum canon line of 4096 chars when the mode is switched to
+ * non-canonical.
+ *
+ * n_tty_receive_buf()/producer path:
+ * claims non-exclusive termios_rwsem
+ * publishes commit_head or canon_head
+ */
static int
n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count, int flow)
{
struct n_tty_data *ldata = tty->disc_data;
- int room, n, rcvd = 0;
+ int room, n, rcvd = 0, overflow;
down_read(&tty->termios_rwsem);
while (1) {
- room = receive_room(tty);
+ /*
+ * When PARMRK is set, each input char may take up to 3 chars
+ * in the read buf; reduce the buffer space avail by 3x
+ *
+ * If we are doing input canonicalization, and there are no
+ * pending newlines, let characters through without limit, so
+ * that erase characters will be handled. Other excess
+ * characters will be beeped.
+ *
+ * paired with store in *_copy_from_read_buf() -- guarantees
+ * the consumer has loaded the data in read_buf up to the new
+ * read_tail (so this producer will not overwrite unread data)
+ */
+ size_t tail = smp_load_acquire(&ldata->read_tail);
+
+ room = N_TTY_BUF_SIZE - (ldata->read_head - tail);
+ if (I_PARMRK(tty))
+ room = (room + 2) / 3;
+ room--;
+ if (room <= 0) {
+ overflow = ldata->icanon && ldata->canon_head == tail;
+ if (overflow && room < 0)
+ ldata->read_head--;
+ room = overflow;
+ ldata->no_room = flow && !room;
+ } else
+ overflow = 0;
+
n = min(count, room);
- if (!n) {
- if (flow && !room)
- ldata->no_room = 1;
+ if (!n)
break;
- }
- __receive_buf(tty, cp, fp, n);
+
+ /* ignore parity errors if handling overflow */
+ if (!overflow || !fp || *fp != TTY_PARITY)
+ __receive_buf(tty, cp, fp, n);
+
cp += n;
if (fp)
fp += n;
}
tty->receive_room = room;
- n_tty_check_throttle(tty);
+
+ /* Unthrottle if handling overflow on pty */
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
+ if (overflow) {
+ tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE);
+ tty_unthrottle_safe(tty);
+ __tty_set_flow_change(tty, 0);
+ }
+ } else
+ n_tty_check_throttle(tty);
+
up_read(&tty->termios_rwsem);
return rcvd;
ldata->canon_head = ldata->read_head;
ldata->push = 1;
}
+ ldata->commit_head = ldata->read_head;
ldata->erasing = 0;
ldata->lnext = 0;
}
else
ldata->real_raw = 0;
}
- n_tty_set_room(tty);
/*
* Fix tty hang when I_IXON(tty) is cleared, but the tty
* been stopped by STOP_CHAR(tty) before it.
if (ldata->icanon && !L_EXTPROC(tty))
return ldata->canon_head != ldata->read_tail;
else
- return read_cnt(ldata) >= amt;
+ return ldata->commit_head - ldata->read_tail >= amt;
}
/**
int retval;
size_t n;
bool is_eof;
+ size_t head = smp_load_acquire(&ldata->commit_head);
size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
retval = 0;
- n = min(read_cnt(ldata), N_TTY_BUF_SIZE - tail);
+ n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
n = min(*nr, n);
if (n) {
retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
ldata->icanon);
- ldata->read_tail += n;
+ smp_store_release(&ldata->read_tail, ldata->read_tail + n);
/* Turn single EOF into zero-length read */
- if (L_EXTPROC(tty) && ldata->icanon && is_eof && !read_cnt(ldata))
+ if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
+ (head == ldata->read_tail))
n = 0;
*b += n;
*nr -= n;
bool eof_push = 0;
/* N.B. avoid overrun if nr == 0 */
- n = min(*nr, read_cnt(ldata));
+ n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
if (!n)
return 0;
if (found)
clear_bit(eol, ldata->read_flags);
- smp_mb__after_atomic();
- ldata->read_tail += c;
+ smp_store_release(&ldata->read_tail, ldata->read_tail + c);
if (found) {
if (!ldata->push)
ssize_t retval = 0;
long timeout;
int packet;
+ size_t tail;
c = job_control(tty, file);
if (c < 0)
}
packet = tty->packet;
+ tail = ldata->read_tail;
add_wait_queue(&tty->read_wait, &wait);
while (nr) {
retval = -ERESTARTSYS;
break;
}
- n_tty_set_room(tty);
up_read(&tty->termios_rwsem);
timeout = wait_woken(&wait, TASK_INTERRUPTIBLE,
if (time)
timeout = time;
}
- n_tty_set_room(tty);
+ if (tail != ldata->read_tail)
+ n_tty_kick_worker(tty);
up_read(&tty->termios_rwsem);
remove_wait_queue(&tty->read_wait, &wait);
projects / firefly-linux-kernel-4.4.55.git / blobdiff