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-rw-r--r--drivers/tty/n_tty.c91
-rw-r--r--drivers/tty/tty_buffer.c59
-rw-r--r--drivers/tty/tty_port.c21
3 files changed, 146 insertions, 25 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 640c9e871044..8d80384df874 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -118,6 +118,9 @@ struct n_tty_data {
size_t read_tail;
size_t line_start;
+ /* # of chars looked ahead (to find software flow control chars) */
+ size_t lookahead_count;
+
/* protected by output lock */
unsigned int column;
unsigned int canon_column;
@@ -333,6 +336,8 @@ static void reset_buffer_flags(struct n_tty_data *ldata)
ldata->erasing = 0;
bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE);
ldata->push = 0;
+
+ ldata->lookahead_count = 0;
}
static void n_tty_packet_mode_flush(struct tty_struct *tty)
@@ -1225,12 +1230,30 @@ static bool n_tty_is_char_flow_ctrl(struct tty_struct *tty, unsigned char c)
return c == START_CHAR(tty) || c == STOP_CHAR(tty);
}
-/* Returns true if c is consumed as flow-control character */
-static bool n_tty_receive_char_flow_ctrl(struct tty_struct *tty, unsigned char c)
+/**
+ * n_tty_receive_char_flow_ctrl - receive flow control chars
+ * @tty: terminal device
+ * @c: character
+ * @lookahead_done: lookahead has processed this character already
+ *
+ * Receive and process flow control character actions.
+ *
+ * In case lookahead for flow control chars already handled the character in
+ * advance to the normal receive, the actions are skipped during normal
+ * receive.
+ *
+ * Returns true if @c is consumed as flow-control character, the character
+ * must not be treated as normal character.
+ */
+static bool n_tty_receive_char_flow_ctrl(struct tty_struct *tty, unsigned char c,
+ bool lookahead_done)
{
if (!n_tty_is_char_flow_ctrl(tty, c))
return false;
+ if (lookahead_done)
+ return true;
+
if (c == START_CHAR(tty)) {
start_tty(tty);
process_echoes(tty);
@@ -1242,11 +1265,12 @@ static bool n_tty_receive_char_flow_ctrl(struct tty_struct *tty, unsigned char c
return true;
}
-static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
+static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c,
+ bool lookahead_done)
{
struct n_tty_data *ldata = tty->disc_data;
- if (I_IXON(tty) && n_tty_receive_char_flow_ctrl(tty, c))
+ if (I_IXON(tty) && n_tty_receive_char_flow_ctrl(tty, c, lookahead_done))
return;
if (L_ISIG(tty)) {
@@ -1401,7 +1425,8 @@ static void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
put_tty_queue(c, ldata);
}
-static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
+static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c,
+ bool lookahead_done)
{
if (I_ISTRIP(tty))
c &= 0x7f;
@@ -1409,9 +1434,12 @@ static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c)
c = tolower(c);
if (I_IXON(tty)) {
- if (c == STOP_CHAR(tty))
- stop_tty(tty);
- else if (c == START_CHAR(tty) ||
+ if (c == STOP_CHAR(tty)) {
+ if (!lookahead_done)
+ stop_tty(tty);
+ } else if (c == START_CHAR(tty) && lookahead_done) {
+ return;
+ } else if (c == START_CHAR(tty) ||
(tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) &&
c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) &&
c != SUSP_CHAR(tty))) {
@@ -1457,6 +1485,27 @@ n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
n_tty_receive_char_flagged(tty, c, flag);
}
+/* Caller must ensure count > 0 */
+static void n_tty_lookahead_flow_ctrl(struct tty_struct *tty, const unsigned char *cp,
+ const unsigned char *fp, unsigned int count)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+ unsigned char flag = TTY_NORMAL;
+
+ ldata->lookahead_count += count;
+
+ if (!I_IXON(tty))
+ return;
+
+ while (count--) {
+ if (fp)
+ flag = *fp++;
+ if (likely(flag == TTY_NORMAL))
+ n_tty_receive_char_flow_ctrl(tty, *cp, false);
+ cp++;
+ }
+}
+
static void
n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp,
const char *fp, int count)
@@ -1496,7 +1545,7 @@ n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp,
static void
n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
- const char *fp, int count)
+ const char *fp, int count, bool lookahead_done)
{
char flag = TTY_NORMAL;
@@ -1504,12 +1553,12 @@ n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp,
if (fp)
flag = *fp++;
if (likely(flag == TTY_NORMAL))
- n_tty_receive_char_closing(tty, *cp++);
+ n_tty_receive_char_closing(tty, *cp++, lookahead_done);
}
}
static void n_tty_receive_buf_standard(struct tty_struct *tty,
- const unsigned char *cp, const char *fp, int count)
+ const unsigned char *cp, const char *fp, int count, bool lookahead_done)
{
struct n_tty_data *ldata = tty->disc_data;
char flag = TTY_NORMAL;
@@ -1540,7 +1589,7 @@ static void n_tty_receive_buf_standard(struct tty_struct *tty,
}
if (test_bit(c, ldata->char_map))
- n_tty_receive_char_special(tty, c);
+ n_tty_receive_char_special(tty, c, lookahead_done);
else
n_tty_receive_char(tty, c);
}
@@ -1551,21 +1600,30 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
{
struct n_tty_data *ldata = tty->disc_data;
bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty));
+ size_t la_count = min_t(size_t, ldata->lookahead_count, count);
if (ldata->real_raw)
n_tty_receive_buf_real_raw(tty, cp, fp, count);
else if (ldata->raw || (L_EXTPROC(tty) && !preops))
n_tty_receive_buf_raw(tty, cp, fp, count);
- else if (tty->closing && !L_EXTPROC(tty))
- n_tty_receive_buf_closing(tty, cp, fp, count);
- else {
- n_tty_receive_buf_standard(tty, cp, fp, count);
+ else if (tty->closing && !L_EXTPROC(tty)) {
+ if (la_count > 0)
+ n_tty_receive_buf_closing(tty, cp, fp, la_count, true);
+ if (count > la_count)
+ n_tty_receive_buf_closing(tty, cp, fp, count - la_count, false);
+ } else {
+ if (la_count > 0)
+ n_tty_receive_buf_standard(tty, cp, fp, la_count, true);
+ if (count > la_count)
+ n_tty_receive_buf_standard(tty, cp, fp, count - la_count, false);
flush_echoes(tty);
if (tty->ops->flush_chars)
tty->ops->flush_chars(tty);
}
+ ldata->lookahead_count -= la_count;
+
if (ldata->icanon && !L_EXTPROC(tty))
return;
@@ -2446,6 +2504,7 @@ static struct tty_ldisc_ops n_tty_ops = {
.receive_buf = n_tty_receive_buf,
.write_wakeup = n_tty_write_wakeup,
.receive_buf2 = n_tty_receive_buf2,
+ .lookahead_buf = n_tty_lookahead_flow_ctrl,
};
/**
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index bfa431a8e690..754fa43670cc 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -5,6 +5,7 @@
#include <linux/types.h>
#include <linux/errno.h>
+#include <linux/minmax.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
@@ -104,6 +105,7 @@ static void tty_buffer_reset(struct tty_buffer *p, size_t size)
p->size = size;
p->next = NULL;
p->commit = 0;
+ p->lookahead = 0;
p->read = 0;
p->flags = 0;
}
@@ -234,6 +236,7 @@ void tty_buffer_flush(struct tty_struct *tty, struct tty_ldisc *ld)
buf->head = next;
}
buf->head->read = buf->head->commit;
+ buf->head->lookahead = buf->head->read;
if (ld && ld->ops->flush_buffer)
ld->ops->flush_buffer(tty);
@@ -276,13 +279,15 @@ static int __tty_buffer_request_room(struct tty_port *port, size_t size,
if (n != NULL) {
n->flags = flags;
buf->tail = n;
- /* paired w/ acquire in flush_to_ldisc(); ensures
- * flush_to_ldisc() sees buffer data.
+ /*
+ * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
+ * ensures they see all buffer data.
*/
smp_store_release(&b->commit, b->used);
- /* paired w/ acquire in flush_to_ldisc(); ensures the
- * latest commit value can be read before the head is
- * advanced to the next buffer
+ /*
+ * Paired w/ acquire in flush_to_ldisc() and lookahead_bufs()
+ * ensures the latest commit value can be read before the head
+ * is advanced to the next buffer.
*/
smp_store_release(&b->next, n);
} else if (change)
@@ -459,6 +464,40 @@ int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
}
EXPORT_SYMBOL_GPL(tty_ldisc_receive_buf);
+static void lookahead_bufs(struct tty_port *port, struct tty_buffer *head)
+{
+ head->lookahead = max(head->lookahead, head->read);
+
+ while (head) {
+ struct tty_buffer *next;
+ unsigned char *p, *f = NULL;
+ unsigned int count;
+
+ /*
+ * Paired w/ release in __tty_buffer_request_room();
+ * ensures commit value read is not stale if the head
+ * is advancing to the next buffer.
+ */
+ next = smp_load_acquire(&head->next);
+ /*
+ * Paired w/ release in __tty_buffer_request_room() or in
+ * tty_buffer_flush(); ensures we see the committed buffer data.
+ */
+ count = smp_load_acquire(&head->commit) - head->lookahead;
+ if (!count) {
+ head = next;
+ continue;
+ }
+
+ p = char_buf_ptr(head, head->lookahead);
+ if (~head->flags & TTYB_NORMAL)
+ f = flag_buf_ptr(head, head->lookahead);
+
+ port->client_ops->lookahead_buf(port, p, f, count);
+ head->lookahead += count;
+ }
+}
+
static int
receive_buf(struct tty_port *port, struct tty_buffer *head, int count)
{
@@ -496,7 +535,7 @@ static void flush_to_ldisc(struct work_struct *work)
while (1) {
struct tty_buffer *head = buf->head;
struct tty_buffer *next;
- int count;
+ int count, rcvd;
/* Ldisc or user is trying to gain exclusive access */
if (atomic_read(&buf->priority))
@@ -519,10 +558,12 @@ static void flush_to_ldisc(struct work_struct *work)
continue;
}
- count = receive_buf(port, head, count);
- if (!count)
+ rcvd = receive_buf(port, head, count);
+ head->read += rcvd;
+ if (rcvd < count)
+ lookahead_bufs(port, head);
+ if (!rcvd)
break;
- head->read += count;
if (need_resched())
cond_resched();
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 880608a65773..dce08a6d7b5e 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -43,6 +43,26 @@ static int tty_port_default_receive_buf(struct tty_port *port,
return ret;
}
+static void tty_port_default_lookahead_buf(struct tty_port *port, const unsigned char *p,
+ const unsigned char *f, unsigned int count)
+{
+ struct tty_struct *tty;
+ struct tty_ldisc *disc;
+
+ tty = READ_ONCE(port->itty);
+ if (!tty)
+ return;
+
+ disc = tty_ldisc_ref(tty);
+ if (!disc)
+ return;
+
+ if (disc->ops->lookahead_buf)
+ disc->ops->lookahead_buf(disc->tty, p, f, count);
+
+ tty_ldisc_deref(disc);
+}
+
static void tty_port_default_wakeup(struct tty_port *port)
{
struct tty_struct *tty = tty_port_tty_get(port);
@@ -55,6 +75,7 @@ static void tty_port_default_wakeup(struct tty_port *port)
const struct tty_port_client_operations tty_port_default_client_ops = {
.receive_buf = tty_port_default_receive_buf,
+ .lookahead_buf = tty_port_default_lookahead_buf,
.write_wakeup = tty_port_default_wakeup,
};
EXPORT_SYMBOL_GPL(tty_port_default_client_ops);
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-02 23:57:40 +0000