tty: Don't release tty locks for wait queue sanity check
authorPeter Hurley <peter@hurleysoftware.com>
Wed, 5 Nov 2014 17:12:54 +0000 (12:12 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 6 Nov 2014 02:39:59 +0000 (18:39 -0800)
commitd5e370a4eeb701201bd441b4ec089091dd6f2ce0
tree918798cf6b51da2bb2ca69f602f3929289bdcdec
parent0911261d4cb614ef6900cd2906be2c61a87f43ff
tty: Don't release tty locks for wait queue sanity check

Releasing the tty locks while waiting for the tty wait queues to
be empty is no longer necessary nor desirable. Prior to
"tty: Don't take tty_mutex for tty count changes", dropping the
tty locks was necessary to reestablish the correct lock order between
tty_mutex and the tty locks. Dropping the global tty_mutex was necessary;
otherwise new ttys could not have been opened while waiting.

However, without needing the global tty_mutex held, the tty locks for
the releasing tty can now be held through the sleep. The sanity check
is for abnormal conditions caused by kernel bugs, not for recoverable
errors caused by misbehaving userspace; dropping the tty locks only
allows the tty state to get more sideways.

Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/tty_io.c