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-rw-r--r--drivers/tty/n_tty.c72
-rw-r--r--drivers/tty/tty_buffer.c13
-rw-r--r--drivers/tty/vt/selection.c4
-rw-r--r--include/linux/tty.h13
-rw-r--r--include/linux/tty_ldisc.h13
5 files changed, 82 insertions, 33 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 4bf0fc0843d7..eddeb7889e62 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -79,6 +79,9 @@ struct n_tty_data {
unsigned long overrun_time;
int num_overrun;
+ /* non-atomic */
+ bool no_room;
+
unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;
unsigned char echo_overrun:1;
@@ -114,25 +117,10 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
return put_user(x, ptr);
}
-/**
- * n_tty_set_room - receive space
- * @tty: terminal
- *
- * Updates tty->receive_room to reflect the currently available space
- * in the input buffer, and re-schedules the flip buffer work if space
- * just became available.
- *
- * Locks: Concurrent update is protected with read_lock
- */
-
-static int set_room(struct tty_struct *tty)
+static int receive_room(struct tty_struct *tty)
{
struct n_tty_data *ldata = tty->disc_data;
int left;
- int old_left;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&ldata->read_lock, flags);
if (I_PARMRK(tty)) {
/* Multiply read_cnt by 3, since each byte might take up to
@@ -150,18 +138,27 @@ static int set_room(struct tty_struct *tty)
*/
if (left <= 0)
left = ldata->icanon && !ldata->canon_data;
- old_left = tty->receive_room;
- tty->receive_room = left;
- raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
-
- return left && !old_left;
+ return left;
}
+/**
+ * n_tty_set_room - receive space
+ * @tty: terminal
+ *
+ * Re-schedules the flip buffer work if space just became available.
+ *
+ * Locks: Concurrent update is protected with read_lock
+ */
+
static void n_tty_set_room(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 (set_room(tty)) {
+ if (unlikely(ldata->no_room) && receive_room(tty)) {
+ ldata->no_room = 0;
+
WARN_RATELIMIT(tty->port->itty == NULL,
"scheduling with invalid itty\n");
/* see if ldisc has been killed - if so, this means that
@@ -1408,8 +1405,8 @@ static void n_tty_write_wakeup(struct tty_struct *tty)
* calls one at a time and in order (or using flush_to_ldisc)
*/
-static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
- char *fp, int count)
+static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
{
struct n_tty_data *ldata = tty->disc_data;
const unsigned char *p;
@@ -1464,8 +1461,6 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
tty->ops->flush_chars(tty);
}
- set_room(tty);
-
if ((!ldata->icanon && (ldata->read_cnt >= ldata->minimum_to_wake)) ||
L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
@@ -1480,7 +1475,7 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
*/
while (1) {
tty_set_flow_change(tty, TTY_THROTTLE_SAFE);
- if (tty->receive_room >= TTY_THRESHOLD_THROTTLE)
+ if (receive_room(tty) >= TTY_THRESHOLD_THROTTLE)
break;
if (!tty_throttle_safe(tty))
break;
@@ -1488,6 +1483,28 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
__tty_set_flow_change(tty, 0);
}
+static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
+{
+ __receive_buf(tty, cp, fp, count);
+}
+
+static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
+ char *fp, int count)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+ int room;
+
+ tty->receive_room = room = receive_room(tty);
+ if (!room)
+ ldata->no_room = 1;
+ count = min(count, room);
+ if (count)
+ __receive_buf(tty, cp, fp, count);
+
+ return count;
+}
+
int is_ignored(int sig)
{
return (sigismember(&current->blocked, sig) ||
@@ -2203,6 +2220,7 @@ struct tty_ldisc_ops tty_ldisc_N_TTY = {
.receive_buf = n_tty_receive_buf,
.write_wakeup = n_tty_write_wakeup,
.fasync = n_tty_fasync,
+ .receive_buf2 = n_tty_receive_buf2,
};
/**
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index 6c7a1d043c76..ff1b2e37c3ca 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -407,11 +407,16 @@ static int
receive_buf(struct tty_struct *tty, struct tty_buffer *head, int count)
{
struct tty_ldisc *disc = tty->ldisc;
+ char *p = head->char_buf_ptr + head->read;
+ unsigned char *f = head->flag_buf_ptr + head->read;
- count = min_t(int, count, tty->receive_room);
- if (count)
- disc->ops->receive_buf(tty, head->char_buf_ptr + head->read,
- head->flag_buf_ptr + head->read, count);
+ if (disc->ops->receive_buf2)
+ count = disc->ops->receive_buf2(tty, p, f, count);
+ else {
+ count = min_t(int, count, tty->receive_room);
+ if (count)
+ disc->ops->receive_buf(tty, p, f, count);
+ }
head->read += count;
return count;
}
diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 60b7b6926059..2ca8d6b6514c 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -356,8 +356,8 @@ int paste_selection(struct tty_struct *tty)
continue;
}
count = sel_buffer_lth - pasted;
- count = min(count, tty->receive_room);
- ld->ops->receive_buf(tty, sel_buffer + pasted, NULL, count);
+ count = tty_ldisc_receive_buf(ld, sel_buffer + pasted, NULL,
+ count);
pasted += count;
}
remove_wait_queue(&vc->paste_wait, &wait);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 7269daf7632b..8323ee4f95b9 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -557,6 +557,19 @@ extern void tty_ldisc_init(struct tty_struct *tty);
extern void tty_ldisc_deinit(struct tty_struct *tty);
extern void tty_ldisc_begin(void);
+static inline int tty_ldisc_receive_buf(struct tty_ldisc *ld, unsigned char *p,
+ char *f, int count)
+{
+ if (ld->ops->receive_buf2)
+ count = ld->ops->receive_buf2(ld->tty, p, f, count);
+ else {
+ count = min_t(int, count, ld->tty->receive_room);
+ if (count)
+ ld->ops->receive_buf(ld->tty, p, f, count);
+ }
+ return count;
+}
+
/* n_tty.c */
extern struct tty_ldisc_ops tty_ldisc_N_TTY;
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index 23bdd9debb84..f15c898ff462 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -109,6 +109,17 @@
*
* Tells the discipline that the DCD pin has changed its status.
* Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
+ *
+ * int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
+ * char *fp, int count);
+ *
+ * This function is called by the low-level tty driver to send
+ * characters received by the hardware to the line discpline for
+ * processing. <cp> is a pointer to the buffer of input
+ * character received by the device. <fp> is a pointer to a
+ * pointer of flag bytes which indicate whether a character was
+ * received with a parity error, etc.
+ * If assigned, prefer this function for automatic flow control.
*/
#include <linux/fs.h>
@@ -195,6 +206,8 @@ struct tty_ldisc_ops {
void (*write_wakeup)(struct tty_struct *);
void (*dcd_change)(struct tty_struct *, unsigned int);
void (*fasync)(struct tty_struct *tty, int on);
+ int (*receive_buf2)(struct tty_struct *, const unsigned char *cp,
+ char *fp, int count);
struct module *owner;
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