From: Valdis.Kletnieks@vt.edu
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Joe Perches <joe@perches.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.cz>, Paul Fulghum <paulkf@microgate.com>,
David Howells <dhowells@redhat.com>,
linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] TTY: synclink, small cleanup in dtr_rts()
Date: Tue, 29 Jan 2013 10:55:16 -0500 [thread overview]
Message-ID: <9561.1359474916@turing-police.cc.vt.edu> (raw)
In-Reply-To: Your message of "Sun, 27 Jan 2013 23:19:47 +0300." <20130127201947.GO16282@mwanda>
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On Sun, 27 Jan 2013 23:19:47 +0300, Dan Carpenter said:
> Yeah. I think it would be, but adding bitflags together instead of
> doing bitwise ORs is very common as well.
The fact it's common doesn't mean it's good programming practice,
or even correct. Consider:
#define F_FOO 0x01
#define F_BAR 0x02
#define F_BAZ 0x04
unsigned int flags = F_FOO;
...
flags |= F_BAR;
Now some time later, another code path does this:
flags += F_FOO;
If it was another |, it would be a no harm no foul class of bug.
But how long is it going to take you to figure out who set F_BAZ?
I wonder if there's a way to write a coccinelle patch to find places
where we do arithmetic operations on bitmasks....
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next prev parent reply other threads:[~2013-01-29 15:56 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-27 19:40 [patch] TTY: synclink, small cleanup in dtr_rts() Dan Carpenter
2013-01-27 20:04 ` Joe Perches
2013-01-27 20:16 ` Jiri Slaby
2013-01-27 20:19 ` Dan Carpenter
2013-01-27 21:00 ` Joe Perches
[not found] ` <C8AFB2C4-4974-4265-A41C-A56C71784F39@microgate.com>
2013-01-28 2:21 ` [PATCH] TTY: synclink: Convert + to | for bit operations Joe Perches
2013-01-28 12:06 ` [patch] TTY: synclink, small cleanup in dtr_rts() walter harms
2013-01-29 15:55 ` Valdis.Kletnieks [this message]
2013-01-29 16:13 ` coccinelle and bitmask arithmetic (was: Re: [patch] TTY: synclink, small cleanup in dtr_rts()) Joe Perches
2013-01-29 16:19 ` Julia Lawall
2013-01-29 16:31 ` Joe Perches
2013-01-29 17:30 ` Dan Carpenter
2013-01-29 17:42 ` Dan Carpenter
2013-01-29 17:49 ` Julia Lawall
2013-01-29 18:03 ` Joe Perches
2013-01-30 8:21 ` coccinelle and bitmask arithmetic walter harms
2013-01-30 8:29 ` Joe Perches
2013-01-30 11:14 ` Russell King - ARM Linux
2013-01-30 11:21 ` Julia Lawall
2013-01-30 11:35 ` Russell King - ARM Linux
2013-01-30 16:53 ` Joe Perches
2013-01-30 18:23 ` Russell King - ARM Linux
2013-01-29 18:38 ` coccinelle and bitmask arithmetic (was: Re: [patch] TTY: synclink, small cleanup in dtr_rts()) Julia Lawall
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