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From: Pavel Machek <pavel@ucw.cz>
To: ifaenson@broadcom.com, marcel@holtmann.org,
	kernel list <linux-kernel@vger.kernel.org>,
	gustavo@padovan.org, johan.hedberg@gmail.com,
	linux-bluetooth@vger.kernel.org, sre@kernel.org
Subject: hci_ldisc: suspicious/buggy code
Date: Mon, 17 Oct 2016 23:32:06 +0200	[thread overview]
Message-ID: <20161017213205.GA25141@amd> (raw)

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Hi!

hci_uart_set_flow_control() contains some rather suspicious
code. AFAICT:

set = 0.

Then we do set &= (magic constant). But as set is 0, it stays zero. It
just does not make sense. [Nor does it make sense to do |= on known
value of zero just after else. But that's probably just some artifact
of editing.]

(And if you edit the code anyway, temporary variable to store
TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 | TIOCM_OUT2 | TIOCM_LOOP would
make sense.)

Thanks,
								Pavel


/* Flow control or un-flow control the device */
void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
{
	...
	unsigned int set = 0;
	unsigned int clear = 0;

	if (enable) {
	   	...
		set &= ~(TIOCM_OUT2 | TIOCM_RTS);
		clear = ~set;
		set &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
		       TIOCM_OUT2 | TIOCM_LOOP;
		clear &= TIOCM_DTR | TIOCM_RTS | TIOCM_OUT1 |
			 TIOCM_OUT2 | TIOCM_LOOP;
		status = tty->driver->ops->tiocmset(tty, set, clear);
		BT_DBG("Clearing RTS: %s", status ? "failed" : "success");
	} else {
	       ...	
		set |= (TIOCM_OUT2 | TIOCM_RTS);

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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             reply	other threads:[~2016-10-17 21:32 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-17 21:32 Pavel Machek [this message]
2016-10-17 21:52 ` hci_ldisc: suspicious/buggy code Pavel Machek

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