From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4F38D4C5.9080907@suse.cz> Date: Mon, 13 Feb 2012 10:15:49 +0100 From: Jiri Slaby MIME-Version: 1.0 References: <1329006070-4275-1-git-send-email-richard@nod.at> <20120212191134.GQ23916@ZenIV.linux.org.uk> In-Reply-To: <20120212191134.GQ23916@ZenIV.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Subject: Re: your mail To: Al Viro Cc: Richard Weinberger , linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, gregkh@linuxfoundation.org List-ID: On 02/12/2012 08:11 PM, Al Viro wrote: > On Sun, Feb 12, 2012 at 01:21:10AM +0100, Richard Weinberger wrote: > >> @@ -343,7 +267,7 @@ static irqreturn_t line_write_interrupt(int irq, void *data) >> { >> struct chan *chan = data; >> struct line *line = chan->line; >> - struct tty_struct *tty = line->tty; >> + struct tty_struct *tty = tty_port_tty_get(&line->port); >> int err; >> >> /* >> @@ -354,6 +278,9 @@ static irqreturn_t line_write_interrupt(int irq, void *data) >> spin_lock(&line->lock); >> err = flush_buffer(line); >> if (err == 0) { >> + tty_kref_put(tty); >> + >> + spin_unlock(&line->lock); >> return IRQ_NONE; >> } else if (err < 0) { >> line->head = line->buffer; >> @@ -365,9 +292,12 @@ static irqreturn_t line_write_interrupt(int irq, void *data) >> return IRQ_NONE; >> >> tty_wakeup(tty); >> + tty_kref_put(tty); >> return IRQ_HANDLED; >> } > > That, BTW, smells ugly. Note that return before the last one has no > tty_kref_put() for a very good reason - it's under if (!tty). And > just as line->tty, port->tty can become NULL, so tty_port_tty_get() > can, indeed, return NULL here. Which makes the first tty_kref_put() > oopsable... Nope, it is allowed to call tty_kref_put(NULL). regards, -- js suse labs