From: Peter Hurley Subject: [PATCH -next v2 12/26] tty: Document check_tty_count() requires tty_lock held Date: Wed, 5 Nov 2014 12:12:55 -0500 Message-ID: <1415207589-15967-13-git-send-email-peter@hurleysoftware.com> References: <1413491125-20134-1-git-send-email-peter@hurleysoftware.com> <1415207589-15967-1-git-send-email-peter@hurleysoftware.com> Return-path: In-Reply-To: <1415207589-15967-1-git-send-email-peter@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: Jiri Slaby , One Thousand Gnomes , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Peter Hurley List-Id: linux-serial@vger.kernel.org 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 --- 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