This fixes a BUG_ON-causing regression that was introduced during the

last merge window.
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v2.0.22 (GNU/Linux)
 
 iQIcBAABCAAGBQJTef9lAAoJENNvdpvBGATw7FsP/jZ0ydBmwPrlYgyXDZha1vyw
 THAaU44bqNY9uhxkc/NODSuvAVSVgVIRzAKgmK6oVbPVY69Wo8wkTgfNroE8qnNc
 tDgKZ0g73SAaTCMnjySXklUGmYaopXfRxxtqZ/3xkoH4n+hk6df92neTM9Pcix9T
 ccprop5mTp2giadLYb4o/ZFo93Tzd/QBgNe6WovILSy/NFRgD7+Paf6S+8ybiYu2
 3w2ViLQB0CWxGWHvc4nvLtFJpwxWqDohPhix7b9j9OAKiSwdS2i0A7NdHaqNhSwx
 8bPl5jMu6VXnetDXL1w9416kVsmIwiFe1mI/rehVzEYRv6zily6DaXxpEQsdBexj
 7yLZt9aYY2ZQaTBC82lC553jXeZlRwI290s14zKLnNk+F/C/uo+LJEKRimHdO8qr
 lfm88wWn/fbOSXDI1qXyRsGxxx61lA73ZCgD6j8g90oRM+yJmjYidIXy17DneaNT
 IM7JyYY3FqvxsTtMXXOONLweFbXj5xVMU4TyP4BZ6cLpQYUaZAqr6XWBL47Yy/db
 BSik4DELz9Fv4iS298FnqbOTfEzH7CIYG4hp8bGFHkWY3iZro2jOTvDv6C/RaFPD
 6H3CdqhpdhVbf7v0ZbgTYUOUWDxfUJmZt3gqOIzGIXkWQgsdYJqLHplVXvthUfXC
 IoWMpXu3MXeeG8xabQg9
 =ZFSi
 -----END PGP SIGNATURE-----

Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull /dev/random fix from Ted Ts'o:
 "This fixes a BUG_ON-causing regression that was introduced during the
  last merge window"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: fix BUG_ON caused by accounting simplification

drivers/char/random.c

@@ -995,8 +995,11 @@ retry:
 		ibytes = min_t(size_t, ibytes, have_bytes - reserved);
 	if (ibytes < min)
 		ibytes = 0;
-	entropy_count = max_t(int, 0,
-			      entropy_count - (ibytes << (ENTROPY_SHIFT + 3)));
+	if (have_bytes >= ibytes + reserved)
+		entropy_count -= ibytes << (ENTROPY_SHIFT + 3);
+	else
+		entropy_count = reserved << (ENTROPY_SHIFT + 3);
+
 	if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
 		goto retry;