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| author | Peter Hurley <peter@hurleysoftware.com> | 2016-01-09 21:13:45 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-01-26 23:17:54 -0800 |
| commit | 7f22f6c935cda600660e623a411fe380015d28d9 (patch) | |
| tree | 1083661f1cad2ddd47a7770b2d6f4470da37d157 /drivers/tty | |
| parent | 0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 (diff) | |
| download | lwn-7f22f6c935cda600660e623a411fe380015d28d9.tar.gz lwn-7f22f6c935cda600660e623a411fe380015d28d9.zip | |
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.c | 12 |
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); |