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checkpatch: try to avoid mask and shift errors

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Shift has a higher precedence that mask so warn when a mask then shift
operation is done without parentheses around the mask.

This test works well for a right shift, but the left shift is pretty
commonly done correctly so only warn on the right shift.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joe Perches 2014-12-10 15:51:46 -08:00 committed by Linus Torvalds
parent 36061e3806
commit abb08a5388
1 changed files with 8 additions and 0 deletions
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scripts/checkpatch.pl
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@ -4482,6 +4482,14 @@ sub process {
}
}
# check for mask then right shift without a parentheses
if ($^V && $^V ge 5.10.0 &&
$line =~ /$LvalOrFunc\s*\&\s*($LvalOrFunc)\s*>>/ &&
$4 !~ /^\&/) { # $LvalOrFunc may be &foo, ignore if so
WARN("MASK_THEN_SHIFT",
"Possible precedence defect with mask then right shift - may need parentheses\n" . $herecurr);
}
# check for bad placement of section $InitAttribute (e.g.: __initdata)
if ($line =~ /(\b$InitAttribute\b)/) {
my $attr = $1;