n_tty: Factor canonical mode copy from n_tty_read()
Simplify n_tty_read(); extract complex copy algorithm
into separate function, canon_copy_to_user().
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index eddeb78..7fd7774 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1747,6 +1747,62 @@
return retval;
}
+/**
+ * canon_copy_to_user - copy read data in canonical mode
+ * @tty: terminal device
+ * @b: user data
+ * @nr: size of data
+ *
+ * Helper function for n_tty_read. It is only called when ICANON is on;
+ * it copies characters one at a time from the read buffer to the user
+ * space buffer.
+ *
+ * Called under the atomic_read_lock mutex
+ */
+
+static int canon_copy_to_user(struct tty_struct *tty,
+ unsigned char __user **b,
+ size_t *nr)
+{
+ struct n_tty_data *ldata = tty->disc_data;
+ unsigned long flags;
+ int eol, c;
+
+ /* N.B. avoid overrun if nr == 0 */
+ raw_spin_lock_irqsave(&ldata->read_lock, flags);
+ while (*nr && ldata->read_cnt) {
+
+ eol = test_and_clear_bit(ldata->read_tail, ldata->read_flags);
+ c = ldata->read_buf[ldata->read_tail];
+ ldata->read_tail = (ldata->read_tail+1) & (N_TTY_BUF_SIZE-1);
+ ldata->read_cnt--;
+ if (eol) {
+ /* this test should be redundant:
+ * we shouldn't be reading data if
+ * canon_data is 0
+ */
+ if (--ldata->canon_data < 0)
+ ldata->canon_data = 0;
+ }
+ raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
+
+ if (!eol || (c != __DISABLED_CHAR)) {
+ if (tty_put_user(tty, c, *b))
+ return -EFAULT;
+ *b += 1;
+ *nr -= 1;
+ }
+ if (eol) {
+ tty_audit_push(tty);
+ return 0;
+ }
+ raw_spin_lock_irqsave(&ldata->read_lock, flags);
+ }
+ raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
+
+ return 0;
+}
+
extern ssize_t redirected_tty_write(struct file *, const char __user *,
size_t, loff_t *);
@@ -1916,44 +1972,7 @@
}
if (ldata->icanon && !L_EXTPROC(tty)) {
- /* N.B. avoid overrun if nr == 0 */
- raw_spin_lock_irqsave(&ldata->read_lock, flags);
- while (nr && ldata->read_cnt) {
- int eol;
-
- eol = test_and_clear_bit(ldata->read_tail,
- ldata->read_flags);
- c = ldata->read_buf[ldata->read_tail];
- ldata->read_tail = ((ldata->read_tail+1) &
- (N_TTY_BUF_SIZE-1));
- ldata->read_cnt--;
- if (eol) {
- /* this test should be redundant:
- * we shouldn't be reading data if
- * canon_data is 0
- */
- if (--ldata->canon_data < 0)
- ldata->canon_data = 0;
- }
- raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
-
- if (!eol || (c != __DISABLED_CHAR)) {
- if (tty_put_user(tty, c, b++)) {
- retval = -EFAULT;
- b--;
- raw_spin_lock_irqsave(&ldata->read_lock, flags);
- break;
- }
- nr--;
- }
- if (eol) {
- tty_audit_push(tty);
- raw_spin_lock_irqsave(&ldata->read_lock, flags);
- break;
- }
- raw_spin_lock_irqsave(&ldata->read_lock, flags);
- }
- raw_spin_unlock_irqrestore(&ldata->read_lock, flags);
+ retval = canon_copy_to_user(tty, &b, &nr);
if (retval)
break;
} else {