Messages in this thread Patch in this message | | | From | Peter Hurley <> | Subject | [PATCH 12/12] tty: Retry failed reopen if tty teardown in-progress | Date | Fri, 27 Nov 2015 21:25:57 -0500 |
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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> --- drivers/tty/tty_io.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index eb391d4..09e8d4f 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1465,13 +1465,13 @@ 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; @@ -2095,8 +2095,13 @@ retry_open: tty = tty_open_by_driver(device, inode, filp); if (IS_ERR(tty)) { + tty_free_file(filp); retval = PTR_ERR(tty); - goto err_file; + if (retval != -EAGAIN || signal_pending(current)) + return retval; + + schedule(); + goto retry_open; } tty_add_file(tty, filp); @@ -2165,9 +2170,6 @@ retry_open: read_unlock(&tasklist_lock); tty_unlock(tty); return 0; -err_file: - tty_free_file(filp); - return retval; } -- 2.6.3
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