1 files changed, 37 insertions, 42 deletions

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 13844261cd5f..d9a5fc28fef4 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -162,14 +162,25 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
 	return put_user(x, ptr);
 }
 
-static inline int tty_copy_to_user(struct tty_struct *tty,
-					void __user *to,
-					const void *from,
-					unsigned long n)
+static int tty_copy_to_user(struct tty_struct *tty, void __user *to,
+			    size_t tail, size_t n)
 {
 	struct n_tty_data *ldata = tty->disc_data;
+	size_t size = N_TTY_BUF_SIZE - tail;
+	const void *from = read_buf_addr(ldata, tail);
+	int uncopied;
 
-	tty_audit_add_data(tty, to, n, ldata->icanon);
+	if (n > size) {
+		tty_audit_add_data(tty, from, size, ldata->icanon);
+		uncopied = copy_to_user(to, from, size);
+		if (uncopied)
+			return uncopied;
+		to += size;
+		n -= size;
+		from = ldata->read_buf;
+	}
+
+	tty_audit_add_data(tty, from, n, ldata->icanon);
 	return copy_to_user(to, from, n);
 }
 
@@ -1201,9 +1212,7 @@ static void n_tty_receive_overrun(struct tty_struct *tty)
 	ldata->num_overrun++;
 	if (time_after(jiffies, ldata->overrun_time + HZ) ||
 			time_after(ldata->overrun_time, jiffies)) {
-		printk(KERN_WARNING "%s: %d input overrun(s)\n",
-			tty_name(tty),
-			ldata->num_overrun);
+		tty_warn(tty, "%d input overrun(s)\n", ldata->num_overrun);
 		ldata->overrun_time = jiffies;
 		ldata->num_overrun = 0;
 	}
@@ -1486,8 +1495,7 @@ n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
 		n_tty_receive_overrun(tty);
 		break;
 	default:
-		printk(KERN_ERR "%s: unknown flag %d\n",
-		       tty_name(tty), flag);
+		tty_err(tty, "unknown flag %d\n", flag);
 		break;
 	}
 }
@@ -2006,11 +2014,11 @@ static int copy_from_read_buf(struct tty_struct *tty,
 	n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail);
 	n = min(*nr, n);
 	if (n) {
-		retval = copy_to_user(*b, read_buf_addr(ldata, tail), n);
+		const unsigned char *from = read_buf_addr(ldata, tail);
+		retval = copy_to_user(*b, from, n);
 		n -= retval;
-		is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
-		tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
-				ldata->icanon);
+		is_eof = n == 1 && *from == EOF_CHAR(tty);
+		tty_audit_add_data(tty, from, n, ldata->icanon);
 		smp_store_release(&ldata->read_tail, ldata->read_tail + n);
 		/* Turn single EOF into zero-length read */
 		if (L_EXTPROC(tty) && ldata->icanon && is_eof &&
@@ -2054,13 +2062,13 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	size_t eol;
 	size_t tail;
 	int ret, found = 0;
-	bool eof_push = 0;
 
 	/* N.B. avoid overrun if nr == 0 */
-	n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
-	if (!n)
+	if (!*nr)
 		return 0;
 
+	n = min(*nr + 1, smp_load_acquire(&ldata->canon_head) - ldata->read_tail);
+
 	tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1);
 	size = min_t(size_t, tail + n, N_TTY_BUF_SIZE);
 
@@ -2072,34 +2080,24 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 	if (eol == N_TTY_BUF_SIZE && more) {
 		/* scan wrapped without finding set bit */
 		eol = find_next_bit(ldata->read_flags, more, 0);
-		if (eol != more)
-			found = 1;
-	} else if (eol != size)
-		found = 1;
+		found = eol != more;
+	} else
+		found = eol != size;
 
-	size = N_TTY_BUF_SIZE - tail;
 	n = eol - tail;
 	if (n > N_TTY_BUF_SIZE)
 		n += N_TTY_BUF_SIZE;
-	n += found;
-	c = n;
+	c = n + found;
 
-	if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) {
-		n--;
-		eof_push = !n && ldata->read_tail != ldata->line_start;
+	if (!found || read_buf(ldata, eol) != __DISABLED_CHAR) {
+		c = min(*nr, c);
+		n = c;
 	}
 
-	n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n",
-		    __func__, eol, found, n, c, size, more);
-
-	if (n > size) {
-		ret = tty_copy_to_user(tty, *b, read_buf_addr(ldata, tail), size);
-		if (ret)
-			return -EFAULT;
-		ret = tty_copy_to_user(tty, *b + size, ldata->read_buf, n - size);
-	} else
-		ret = tty_copy_to_user(tty, *b, read_buf_addr(ldata, tail), n);
+	n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu tail:%zu more:%zu\n",
+		    __func__, eol, found, n, c, tail, more);
 
+	ret = tty_copy_to_user(tty, *b, tail, n);
 	if (ret)
 		return -EFAULT;
 	*b += n;
@@ -2116,7 +2114,7 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
 			ldata->push = 0;
 		tty_audit_push(tty);
 	}
-	return eof_push ? -EAGAIN : 0;
+	return 0;
 }
 
 extern ssize_t redirected_tty_write(struct file *, const char __user *,
@@ -2273,10 +2271,7 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
 
 		if (ldata->icanon && !L_EXTPROC(tty)) {
 			retval = canon_copy_from_read_buf(tty, &b, &nr);
-			if (retval == -EAGAIN) {
-				retval = 0;
-				continue;
-			} else if (retval)
+			if (retval)
 				break;
 		} else {
 			int uncopied;