Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756208Ab2JRUb6 (ORCPT ); Thu, 18 Oct 2012 16:31:58 -0400 Received: from mail.pripojeni.net ([178.22.112.14]:56796 "EHLO smtp.pripojeni.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754340Ab2JRU0y (ORCPT ); Thu, 18 Oct 2012 16:26:54 -0400 From: Jiri Slaby To: gregkh@linuxfoundation.org Cc: alan@linux.intel.com, linux-kernel@vger.kernel.org, jirislaby@gmail.com Subject: [PATCH 10/21] TTY: n_tty, remove bogus checks Date: Thu, 18 Oct 2012 22:26:36 +0200 Message-Id: <1350592007-9216-11-git-send-email-jslaby@suse.cz> X-Mailer: git-send-email 1.7.12.3 In-Reply-To: <1350592007-9216-1-git-send-email-jslaby@suse.cz> References: <1350592007-9216-1-git-send-email-jslaby@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2931 Lines: 84 * BUG_ON(!tty) in n_tty_set_termios -- it cannot be called with tty == NULL. It is called from two call sites. First, from n_tty_open where we have a valid tty. Second, as ld->ops->set_termios from tty_set_termios. But there we have a valid tty too. * if (!tty) in n_tty_open -- why would the TTY layer call ldisc's open with an invalid TTY? No it indeed does not. All call sites have a tty and dereference that. * BUG_ON(!tty->read_buf) in n_tty_read -- this used to be a valid check. The ldisc handling was broken some time ago when I added the check to ensure everything is OK. It still can catch the case, but no later than we move the buffer to ldisc data. Then there will be no read_buf in tty_struct, i.e. nothing to check for. * if (!tty->read_buf) in n_tty_receive_buf -- this should never happen. All callers of ldisc->ops->receive_ops should hold a reference to an ldisc and close (which frees read_buf) cannot be called until the reference is dropped. * if (WARN_ON(!tty->read_buf)) in n_tty_read -- the same as in the previous case. Signed-off-by: Jiri Slaby --- drivers/tty/n_tty.c | 12 ------------ 1 file changed, 12 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index f27289d..ceae074 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -1375,9 +1375,6 @@ static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, char buf[64]; unsigned long cpuflags; - if (!tty->read_buf) - return; - if (tty->real_raw) { spin_lock_irqsave(&tty->read_lock, cpuflags); i = min(N_TTY_BUF_SIZE - tty->read_cnt, @@ -1471,7 +1468,6 @@ int is_ignored(int sig) static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) { int canon_change = 1; - BUG_ON(!tty); if (old) canon_change = (old->c_lflag ^ tty->termios.c_lflag) & ICANON; @@ -1579,9 +1575,6 @@ static void n_tty_close(struct tty_struct *tty) static int n_tty_open(struct tty_struct *tty) { - if (!tty) - return -EINVAL; - /* These are ugly. Currently a malloc failure here can panic */ tty->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); tty->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL); @@ -1736,10 +1729,6 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, int packet; do_it_again: - - if (WARN_ON(!tty->read_buf)) - return -EAGAIN; - c = job_control(tty, file); if (c < 0) return c; @@ -1825,7 +1814,6 @@ do_it_again: /* FIXME: does n_tty_set_room need locking ? */ n_tty_set_room(tty); timeout = schedule_timeout(timeout); - BUG_ON(!tty->read_buf); continue; } __set_current_state(TASK_RUNNING); -- 1.7.12.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/