bna: remove unreasonable iocpf timer start

[cascardo/linux.git] / drivers / tty / n_tty.c

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index cf6e0f2..cc57a3a 100644 (file)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1949,6 +1949,18 @@ static inline int input_available_p(struct tty_struct *tty, int poll)
                return ldata->commit_head - ldata->read_tail >= amt;
 }
 
+static inline int check_other_done(struct tty_struct *tty)
+{
+       int done = test_bit(TTY_OTHER_DONE, &tty->flags);
+       if (done) {
+               /* paired with cmpxchg() in check_other_closed(); ensures
+                * read buffer head index is not stale
+                */
+               smp_mb__after_atomic();
+       }
+       return done;
+}
+
 /**
  *     copy_from_read_buf      -       copy read data directly
  *     @tty: terminal device
@@ -2167,7 +2179,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
        struct n_tty_data *ldata = tty->disc_data;
        unsigned char __user *b = buf;
        DEFINE_WAIT_FUNC(wait, woken_wake_function);
-       int c;
+       int c, done;
        int minimum, time;
        ssize_t retval = 0;
        long timeout;
@@ -2235,8 +2247,10 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
                    ((minimum - (b - buf)) >= 1))
                        ldata->minimum_to_wake = (minimum - (b - buf));
 
+               done = check_other_done(tty);
+
                if (!input_available_p(tty, 0)) {
-                       if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
+                       if (done) {
                                retval = -EIO;
                                break;
                        }
@@ -2443,12 +2457,12 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 
        poll_wait(file, &tty->read_wait, wait);
        poll_wait(file, &tty->write_wait, wait);
+       if (check_other_done(tty))
+               mask |= POLLHUP;
        if (input_available_p(tty, 1))
                mask |= POLLIN | POLLRDNORM;
        if (tty->packet && tty->link->ctrl_status)
                mask |= POLLPRI | POLLIN | POLLRDNORM;
-       if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
-               mask |= POLLHUP;
        if (tty_hung_up_p(file))
                mask |= POLLHUP;
        if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {