[PATCH -next v2 12/26] tty: Document check_tty_count() requires tty_lock held

Peter Hurley
2014-11-05T17:50:49Z

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>
---
drivers/tty/tty_io.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 276d939..41eeee0 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -275,6 +275,7 @@ int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
return 0;
}

+/* Caller must hold tty_lock */
static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
--
2.1.3