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path: root/drivers/tty/n_tty.c
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Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c29
1 files changed, 24 insertions, 5 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ee1c268f5f9d..8c0b7b42319c 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -92,10 +92,18 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
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 left;
int old_left;
+ /* tty->read_cnt is not read locked ? */
+ 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 - tty->read_cnt * 3 - 1;
+ } else
+ left = N_TTY_BUF_SIZE - tty->read_cnt - 1;
+
/*
* If we are doing input canonicalization, and there are no
* pending newlines, let characters through without limit, so
@@ -1432,6 +1440,12 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
*/
if (tty->receive_room < TTY_THRESHOLD_THROTTLE)
tty_throttle(tty);
+
+ /* FIXME: there is a tiny race here if the receive room check runs
+ before the other work executes and empties the buffer (upping
+ the receiving room and unthrottling. We then throttle and get
+ stuck. This has been observed and traced down by Vincent Pillet/
+ We need to address this when we sort out out the rx path locking */
}
int is_ignored(int sig)
@@ -1460,7 +1474,7 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
BUG_ON(!tty);
if (old)
- canon_change = (old->c_lflag ^ tty->termios->c_lflag) & ICANON;
+ canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON;
if (canon_change) {
memset(&tty->read_flags, 0, sizeof tty->read_flags);
tty->canon_head = tty->read_tail;
@@ -1728,7 +1742,8 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
do_it_again:
- BUG_ON(!tty->read_buf);
+ if (WARN_ON(!tty->read_buf))
+ return -EAGAIN;
c = job_control(tty, file);
if (c < 0)
@@ -1832,13 +1847,13 @@ do_it_again:
if (tty->icanon && !L_EXTPROC(tty)) {
/* N.B. avoid overrun if nr == 0 */
+ spin_lock_irqsave(&tty->read_lock, flags);
while (nr && tty->read_cnt) {
int eol;
eol = test_and_clear_bit(tty->read_tail,
tty->read_flags);
c = tty->read_buf[tty->read_tail];
- spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = ((tty->read_tail+1) &
(N_TTY_BUF_SIZE-1));
tty->read_cnt--;
@@ -1856,15 +1871,19 @@ do_it_again:
if (tty_put_user(tty, c, b++)) {
retval = -EFAULT;
b--;
+ spin_lock_irqsave(&tty->read_lock, flags);
break;
}
nr--;
}
if (eol) {
tty_audit_push(tty);
+ spin_lock_irqsave(&tty->read_lock, flags);
break;
}
+ spin_lock_irqsave(&tty->read_lock, flags);
}
+ spin_unlock_irqrestore(&tty->read_lock, flags);
if (retval)
break;
} else {