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>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index b008e2b..adbd9ac 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -275,6 +275,7 @@
return 0;
}
+/* Caller must hold tty_lock */
static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT