I was cc'd on a patch where structs were passed by value instead of using pointers to the structs. This can cause defects when the called function modifies the 'passed by value' struct instead of the calling function's struct.
There are what seems to be some false positives for a few of the .h files in include/linux/... where the false positives are for very small structs where the indirection via a pointer might be slower than than the passed by value use. Signed-off-by: Joe Perches <[email protected]> --- scripts/checkpatch.pl | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 34e4683de7a3..7ce0ec9c0d19 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6076,8 +6076,10 @@ sub process { # check for function definitions if ($perl_version_ok && defined $stat && - $stat =~ /^.\s*(?:$Storage\s+)?$Type\s*($Ident)\s*$balanced_parens\s*{/s) { + $stat =~ /^.\s*(?:$Storage\s+)?$Type\s*($Ident)\s*$balanced_parens\s*([\{;])/s) { $context_function = $1; + my $args = $2; + my $term = $3; # check for multiline function definition with misplaced open brace my $ok = 0; @@ -6088,12 +6090,26 @@ sub process { $herectx .= $rl . "\n"; $ok = 1 if ($rl =~ /^[ \+]\{/); $ok = 1 if ($rl =~ /\{/ && $n == 0); - last if $rl =~ /^[ \+].*\{/; + last if ($rl =~ /^[ \+].*[\{;]/); } - if (!$ok) { + if (!$ok && $term eq '{') { ERROR("OPEN_BRACE", "open brace '{' following function definitions go on the next line\n" . $herectx); } + +# check for 'passed by value' uses of a struct or a union that might +# be better 'passed by reference' + + while ($args =~ /(?:$Storage\s+)?($Type)\s*($Ident(?:\s*\[\s*\])?)?\s*,?/g) { + my $type = trim($1); + my $ident = defined($2) ? trim($2) : ""; + if ($type =~ /\b(?:union|struct)\b/ && + !($type =~ /(?:\*|\bconst|\])$/ || + $ident =~ /\]$/)) { + WARN("AGGREGATE_BY_VALUE", + "Unusual 'passed by value' use of '$type'\n" . $herectx); + } + } } # checks for new __setup's
