On Fri, 2014-06-27 at 22:10 +0200, Fabian Frederick wrote:
> Avoid automatic k[mz]alloc with multiplies conversions
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -4427,7 +4427,7 @@ sub process {
> $newfunc = "kcalloc" if ($oldfunc eq "kzalloc");
> if ($a1 =~ /^sizeof\s*\S/ || $a2 =~ /^sizeof\s*\S/) {
> if (WARN("ALLOC_WITH_MULTIPLY",
> - "Prefer $newfunc over $oldfunc with
> multiply\n" . $herecurr) &&
> + "Prefer $newfunc over $oldfunc with
> multiply when arguments are not fixed or come from unvalidated source\n" .
> $herecurr) &&
> $fix) {
> my $r1 = $a1;
> my $r2 = $a2;
I'm not sure of the value of this as I think at some point
if not already today, the compiler will optimize the multiply
away.
But it's probably better to look at the non-sizeof variable
and emit the warning only when it's not $Constant or some
upper-case only macro #define like "\b[A-Z_]+\b" is used.
Maybe something like this:
scripts/checkpatch.pl | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 6c7cbaf..e0d0ead 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4486,22 +4486,23 @@ sub process {
# check for k[mz]alloc with multiplies that could be kmalloc_array/kcalloc
if ($^V && $^V ge 5.10.0 &&
- $line =~
/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/)
{
+ $line =~
/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)\s*,/)
{
my $oldfunc = $3;
my $a1 = $4;
my $a2 = $10;
my $newfunc = "kmalloc_array";
$newfunc = "kcalloc" if ($oldfunc eq "kzalloc");
- if ($a1 =~ /^sizeof\s*\S/ || $a2 =~ /^sizeof\s*\S/) {
+ my $r1 = $a1;
+ my $r2 = $a2;
+ if ($a1 =~ /^sizeof\s*\S/) {
+ $r1 = $a2;
+ $r2 = $a1;
+ }
+ if ($r1 !~ /^sizeof\b/ && $r2 =~ /^sizeof\s*\S/ &&
+ !($r1 =~ /^$Constant$/ || $r1 =~ /^[A-Z_]+$/)) {
if (WARN("ALLOC_WITH_MULTIPLY",
"Prefer $newfunc over $oldfunc with
multiply\n" . $herecurr) &&
$fix) {
- my $r1 = $a1;
- my $r2 = $a2;
- if ($a1 =~ /^sizeof\s*\S/) {
- $r1 = $a2;
- $r2 = $a1;
- }
$fixed[$linenr - 1] =~
s/\b($Lval)\s*\=\s*(?:$balanced_parens)?\s*(k[mz]alloc)\s*\(\s*($FuncArg)\s*\*\s*($FuncArg)/$1
. ' = ' . "$newfunc(" . trim($r1) . ', ' . trim($r2)/e;
}
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