Commit 88bb0de3 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 24a89d1c

drivers/tty/n_tty.c

+57 −38
Original line number Diff line number Diff line
@@ -1747,6 +1747,62 @@ static int copy_from_read_buf(struct tty_struct *tty, 
	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 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, 
		}



		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 {