tree a190857e293df1c08a6627b8c9a42f5e5f6ddbcc
parent d5e370a4eeb701201bd441b4ec089091dd6f2ce0
author Peter Hurley <peter@hurleysoftware.com> 1415207575 -0500
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1415241682 -0800

tty: Document check_tty_count() requires tty_lock held

Holding the tty_lock() is necessary to prevent concurrent changes
to the tty count that may cause it to differ from the open file
list count. The tty_lock() is already held at all call sites.

NB: Note that the check for the pty master tty count is safe because
the slave's tty_lock() is held while decrementing the pty master
tty count.

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>