tty: make receive_buf() return the amout of bytes received
it makes it simpler to keep track of the amount of
bytes received and simplifies how flush_to_ldisc counts
the remaining bytes. It also fixes a bug of lost bytes
on n_tty when flushing too many bytes via the USB
serial gadget driver.
Tested-by: Stefan Bigler <stefan.bigler@keymile.com>
Tested-by: Toby Gray <toby.gray@realvnc.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 47f8cdb..6abc735 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2138,8 +2138,8 @@
gsm->tty = NULL;
}
-static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
- char *fp, int count)
+static unsigned int gsmld_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
{
struct gsm_mux *gsm = tty->disc_data;
const unsigned char *dp;
@@ -2173,6 +2173,8 @@
}
/* FASYNC if needed ? */
/* If clogged call tty_throttle(tty); */
+
+ return count;
}
/**
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c
index cea5603..cac6663 100644
--- a/drivers/tty/n_hdlc.c
+++ b/drivers/tty/n_hdlc.c
@@ -188,8 +188,8 @@
poll_table *wait);
static int n_hdlc_tty_open(struct tty_struct *tty);
static void n_hdlc_tty_close(struct tty_struct *tty);
-static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
- char *fp, int count);
+static unsigned int n_hdlc_tty_receive(struct tty_struct *tty,
+ const __u8 *cp, char *fp, int count);
static void n_hdlc_tty_wakeup(struct tty_struct *tty);
#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
@@ -509,8 +509,8 @@
* Called by tty low level driver when receive data is available. Data is
* interpreted as one HDLC frame.
*/
-static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
- char *flags, int count)
+static unsigned int n_hdlc_tty_receive(struct tty_struct *tty,
+ const __u8 *data, char *flags, int count)
{
register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
register struct n_hdlc_buf *buf;
@@ -521,20 +521,20 @@
/* This can happen if stuff comes in on the backup tty */
if (!n_hdlc || tty != n_hdlc->tty)
- return;
+ return -ENODEV;
/* verify line is using HDLC discipline */
if (n_hdlc->magic != HDLC_MAGIC) {
printk("%s(%d) line not using HDLC discipline\n",
__FILE__,__LINE__);
- return;
+ return -EINVAL;
}
if ( count>maxframe ) {
if (debuglevel >= DEBUG_LEVEL_INFO)
printk("%s(%d) rx count>maxframesize, data discarded\n",
__FILE__,__LINE__);
- return;
+ return -EINVAL;
}
/* get a free HDLC buffer */
@@ -550,7 +550,7 @@
if (debuglevel >= DEBUG_LEVEL_INFO)
printk("%s(%d) no more rx buffers, data discarded\n",
__FILE__,__LINE__);
- return;
+ return -EINVAL;
}
/* copy received data to HDLC buffer */
@@ -565,6 +565,8 @@
if (n_hdlc->tty->fasync != NULL)
kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN);
+ return count;
+
} /* end of n_hdlc_tty_receive() */
/**
diff --git a/drivers/tty/n_r3964.c b/drivers/tty/n_r3964.c
index 5c6c314..a4bc39c 100644
--- a/drivers/tty/n_r3964.c
+++ b/drivers/tty/n_r3964.c
@@ -139,8 +139,8 @@
static void r3964_set_termios(struct tty_struct *tty, struct ktermios *old);
static unsigned int r3964_poll(struct tty_struct *tty, struct file *file,
struct poll_table_struct *wait);
-static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
- char *fp, int count);
+static unsigned int r3964_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count);
static struct tty_ldisc_ops tty_ldisc_N_R3964 = {
.owner = THIS_MODULE,
@@ -1239,8 +1239,8 @@
return result;
}
-static void r3964_receive_buf(struct tty_struct *tty, const unsigned char *cp,
- char *fp, int count)
+static unsigned int r3964_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
{
struct r3964_info *pInfo = tty->disc_data;
const unsigned char *p;
@@ -1257,6 +1257,8 @@
}
}
+
+ return count;
}
MODULE_LICENSE("GPL");
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 0ad3288..95d0a9c 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -81,38 +81,6 @@
return put_user(x, ptr);
}
-/**
- * n_tty_set__room - receive space
- * @tty: terminal
- *
- * Called by the driver to find out how much data it is
- * permitted to feed to the line discipline without any being lost
- * and thus to manage flow control. Not serialized. Answers for the
- * "instant".
- */
-
-static void n_tty_set_room(struct tty_struct *tty)
-{
- /* tty->read_cnt is not read locked ? */
- int left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
- int old_left;
-
- /*
- * 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 = tty->icanon && !tty->canon_data;
- old_left = tty->receive_room;
- tty->receive_room = left;
-
- /* Did this open up the receive buffer? We may need to flip */
- if (left && !old_left)
- schedule_work(&tty->buf.work);
-}
-
static void put_tty_queue_nolock(unsigned char c, struct tty_struct *tty)
{
if (tty->read_cnt < N_TTY_BUF_SIZE) {
@@ -184,7 +152,6 @@
tty->canon_head = tty->canon_data = tty->erasing = 0;
memset(&tty->read_flags, 0, sizeof tty->read_flags);
- n_tty_set_room(tty);
check_unthrottle(tty);
}
@@ -1360,17 +1327,19 @@
* 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 unsigned int n_tty_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
{
const unsigned char *p;
char *f, flags = TTY_NORMAL;
int i;
char buf[64];
unsigned long cpuflags;
+ int left;
+ int ret = 0;
if (!tty->read_buf)
- return;
+ return 0;
if (tty->real_raw) {
spin_lock_irqsave(&tty->read_lock, cpuflags);
@@ -1380,6 +1349,7 @@
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
+ ret += i;
cp += i;
count -= i;
@@ -1389,8 +1359,10 @@
memcpy(tty->read_buf + tty->read_head, cp, i);
tty->read_head = (tty->read_head + i) & (N_TTY_BUF_SIZE-1);
tty->read_cnt += i;
+ ret += i;
spin_unlock_irqrestore(&tty->read_lock, cpuflags);
} else {
+ ret = count;
for (i = count, p = cp, f = fp; i; i--, p++) {
if (f)
flags = *f++;
@@ -1418,8 +1390,6 @@
tty->ops->flush_chars(tty);
}
- n_tty_set_room(tty);
-
if ((!tty->icanon && (tty->read_cnt >= tty->minimum_to_wake)) ||
L_EXTPROC(tty)) {
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
@@ -1432,8 +1402,12 @@
* mode. We don't want to throttle the driver if we're in
* canonical mode and don't have a newline yet!
*/
- if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
+ left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
+
+ if (left < TTY_THRESHOLD_THROTTLE)
tty_throttle(tty);
+
+ return ret;
}
int is_ignored(int sig)
@@ -1477,7 +1451,6 @@
if (test_bit(TTY_HW_COOK_IN, &tty->flags)) {
tty->raw = 1;
tty->real_raw = 1;
- n_tty_set_room(tty);
return;
}
if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) ||
@@ -1530,7 +1503,6 @@
else
tty->real_raw = 0;
}
- n_tty_set_room(tty);
/* The termios change make the tty ready for I/O */
wake_up_interruptible(&tty->write_wait);
wake_up_interruptible(&tty->read_wait);
@@ -1812,8 +1784,6 @@
retval = -ERESTARTSYS;
break;
}
- /* FIXME: does n_tty_set_room need locking ? */
- n_tty_set_room(tty);
timeout = schedule_timeout(timeout);
continue;
}
@@ -1885,10 +1855,8 @@
* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode,
* we won't get any more characters.
*/
- if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE) {
- n_tty_set_room(tty);
+ if (n_tty_chars_in_buffer(tty) <= TTY_THRESHOLD_UNTHROTTLE)
check_unthrottle(tty);
- }
if (b - buf >= minimum)
break;
@@ -1910,7 +1878,6 @@
} else if (test_and_clear_bit(TTY_PUSH, &tty->flags))
goto do_it_again;
- n_tty_set_room(tty);
return retval;
}
diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c
index f1a7918..46de2e0 100644
--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -416,6 +416,7 @@
struct tty_buffer *head, *tail = tty->buf.tail;
int seen_tail = 0;
while ((head = tty->buf.head) != NULL) {
+ int copied;
int count;
char *char_buf;
unsigned char *flag_buf;
@@ -442,17 +443,19 @@
line discipline as we want to empty the queue */
if (test_bit(TTY_FLUSHPENDING, &tty->flags))
break;
- if (!tty->receive_room || seen_tail)
- break;
- if (count > tty->receive_room)
- count = tty->receive_room;
char_buf = head->char_buf_ptr + head->read;
flag_buf = head->flag_buf_ptr + head->read;
- head->read += count;
spin_unlock_irqrestore(&tty->buf.lock, flags);
- disc->ops->receive_buf(tty, char_buf,
+ copied = disc->ops->receive_buf(tty, char_buf,
flag_buf, count);
spin_lock_irqsave(&tty->buf.lock, flags);
+
+ head->read += copied;
+
+ if (copied == 0 || seen_tail) {
+ schedule_work(&tty->buf.work);
+ break;
+ }
}
clear_bit(TTY_FLUSHING, &tty->flags);
}
diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index fb864e7..67b1d0d 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -332,8 +332,7 @@
continue;
}
count = sel_buffer_lth - pasted;
- count = min(count, tty->receive_room);
- tty->ldisc->ops->receive_buf(tty, sel_buffer + pasted,
+ count = tty->ldisc->ops->receive_buf(tty, sel_buffer + pasted,
NULL, count);
pasted += count;
}