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authorPeter Hurley <peter@hurleysoftware.com>2016-01-09 21:13:45 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-01-26 23:17:54 -0800
commit7f22f6c935cda600660e623a411fe380015d28d9 (patch)
tree1083661f1cad2ddd47a7770b2d6f4470da37d157 /drivers/tty
parent0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 (diff)
downloadlinux-7f22f6c935cda600660e623a411fe380015d28d9.tar.bz2
tty: Retry failed reopen if tty teardown in-progress
A small window exists where a tty reopen will observe the tty just prior to imminent teardown (tty->count == 0); in this case, open() returns EIO to userspace. Instead, retry the open after checking for signals and yielding; this interruptible retry loop allows teardown to commence and initialize a new tty on retry. Never retry the BSD master pty reopen; there is no guarantee the pty pair teardown is imminent since the slave file descriptors may remain open indefinitely. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> # 4.4 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/tty_io.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 765935b144d6..a1b36bf545e8 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -1463,13 +1463,13 @@ static int tty_reopen(struct tty_struct *tty)
{
struct tty_driver *driver = tty->driver;
- if (!tty->count)
- return -EIO;
-
if (driver->type == TTY_DRIVER_TYPE_PTY &&
driver->subtype == PTY_TYPE_MASTER)
return -EIO;
+ if (!tty->count)
+ return -EAGAIN;
+
if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
return -EBUSY;
@@ -2088,7 +2088,11 @@ retry_open:
if (IS_ERR(tty)) {
retval = PTR_ERR(tty);
- goto err_file;
+ if (retval != -EAGAIN || signal_pending(current))
+ goto err_file;
+ tty_free_file(filp);
+ schedule();
+ goto retry_open;
}
tty_add_file(tty, filp);