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Date: Wed, 6 Jun 2012 23:41:36 +0200
From: Julia Lawall <Julia.Lawall@...6.fr>
To: Ian Abbott <abbotti@....co.uk>
Cc: kernel-janitors@...r.kernel.org,
Mori Hess <fmhess@...rs.sourceforge.net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
joe@...ches.com, Julia Lawall <julia@...u.dk>
Subject: [PATCH 2/7] drivers/staging/comedi/drivers/me4000.c: adjust suspicious bit operation
From: Julia Lawall <Julia.Lawall@...6.fr>
TRIG_ROUND_NEAREST is 0, so a bit-and with it is always false. The
value TRIG_ROUND_MASK covers the bits of the TRIG_ROUND constants, so
first pick those bits and then make the test using ==.
The same is done for TRIG_ROUND_UP for symmetry, even though bit-and would
be sufficient in this case.
This problem was found using Coccinelle (http://coccinelle.lip6.fr/).
Signed-off-by: Julia Lawall <julia@...u.dk>
---
The TRIG_ROUND_UP case could be left as is, if that is preferred. Or a
temporary variable could be introduced to avoid anding with the mask twice.
Actually, the following code suggests that the mask is not necessary, == would be sufficient:
/* Only rounding flags are implemented */
cmd->flags &= TRIG_ROUND_NEAREST | TRIG_ROUND_UP | TRIG_ROUND_DOWN;
But using the mask is safer, if there are future extensions.
drivers/staging/comedi/drivers/me4000.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/comedi/drivers/me4000.c b/drivers/staging/comedi/drivers/me4000.c
index 8ca1b54..fc60117 100644
--- a/drivers/staging/comedi/drivers/me4000.c
+++ b/drivers/staging/comedi/drivers/me4000.c
@@ -949,10 +949,10 @@ static int ai_round_cmd_args(struct comedi_device *dev,
*init_ticks = (cmd->start_arg * 33) / 1000;
rest = (cmd->start_arg * 33) % 1000;
- if (cmd->flags & TRIG_ROUND_NEAREST) {
+ if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_NEAREST) {
if (rest > 33)
(*init_ticks)++;
- } else if (cmd->flags & TRIG_ROUND_UP) {
+ } else if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_UP) {
if (rest)
(*init_ticks)++;
}
@@ -962,10 +962,10 @@ static int ai_round_cmd_args(struct comedi_device *dev,
*scan_ticks = (cmd->scan_begin_arg * 33) / 1000;
rest = (cmd->scan_begin_arg * 33) % 1000;
- if (cmd->flags & TRIG_ROUND_NEAREST) {
+ if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_NEAREST) {
if (rest > 33)
(*scan_ticks)++;
- } else if (cmd->flags & TRIG_ROUND_UP) {
+ } else if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_UP) {
if (rest)
(*scan_ticks)++;
}
@@ -975,10 +975,10 @@ static int ai_round_cmd_args(struct comedi_device *dev,
*chan_ticks = (cmd->convert_arg * 33) / 1000;
rest = (cmd->convert_arg * 33) % 1000;
- if (cmd->flags & TRIG_ROUND_NEAREST) {
+ if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_NEAREST) {
if (rest > 33)
(*chan_ticks)++;
- } else if (cmd->flags & TRIG_ROUND_UP) {
+ } else if ((cmd->flags & TRIG_ROUND_MASK) == TRIG_ROUND_UP) {
if (rest)
(*chan_ticks)++;
}
--
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