From deb287e7401bbbf7803731805acbda1d983d1999 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Wed, 5 Nov 2014 12:12:55 -0500 Subject: [PATCH] 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 Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- 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 b008e2b38d54..adbd9acf817f 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