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Commit e367455a authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds
Browse files

checkpatch: emit fewer kmalloc_array/kcalloc conversion warnings 



Avoid matching allocs that appear to be known small multiplications of a
sizeof with a constant because gcc as of 4.8 cannot optimize the code in
a calloc() exactly the same way as an alloc().

Look for numeric constants or what appear to be upper case only macro
#defines.

Signed-off-by: default avatarJoe Perches <joe@perches.com>
Reported-by: default avatarTheodore Ts'o <tytso@mit.edu>
Original-patch-by: default avatarFabian Frederick <fabf@skynet.be>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f27c95db

scripts/checkpatch.pl

+9 −8
Original line number Diff line number Diff line
@@ -4487,22 +4487,23 @@ 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/) {

				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;

			}

			if ($r1 !~ /^sizeof\b/ && $r2 =~ /^sizeof\s*\S/ &&

			    !($r1 =~ /^$Constant$/ || $r1 =~ /^[A-Z_][A-Z0-9_]*$/)) {

				if (WARN("ALLOC_WITH_MULTIPLY",

					 "Prefer $newfunc over $oldfunc with multiply\n" . $herecurr) &&

				    $fix) {

					$fixed[$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;



				}