diff options
| -rwxr-xr-x | scripts/checkpatch.pl | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 75349f766b89..e8afe3f765de 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -151,6 +151,24 @@ EOM exit($exitcode); } +my $DO_WHILE_0_ADVICE = q{ + do {} while (0) advice is over-stated in a few situations: + + The more obvious case is macros, like MODULE_PARM_DESC, invoked at + file-scope, where C disallows code (it must be in functions). See + $exceptions if you have one to add by name. + + More troublesome is declarative macros used at top of new scope, + like DECLARE_PER_CPU. These might just compile with a do-while-0 + wrapper, but would be incorrect. Most of these are handled by + detecting struct,union,etc declaration primitives in $exceptions. + + Theres also macros called inside an if (block), which "return" an + expression. These cannot do-while, and need a ({}) wrapper. + + Enjoy this qualification while we work to improve our heuristics. +}; + sub uniq { my %seen; return grep { !$seen{$_}++ } @_; @@ -5883,9 +5901,9 @@ sub process { } } -# multi-statement macros should be enclosed in a do while loop, grab the -# first statement and ensure its the whole macro if its not enclosed -# in a known good container +# Usually multi-statement macros should be enclosed in a do {} while +# (0) loop. Grab the first statement and ensure its the whole macro +# if its not enclosed in a known good container if ($realfile !~ m@/vmlinux.lds.h$@ && $line =~ /^.\s*\#\s*define\s*$Ident(\()?/) { my $ln = $linenr; @@ -5938,10 +5956,13 @@ sub process { my $exceptions = qr{ $Declare| + # named exceptions module_param_named| MODULE_PARM_DESC| DECLARE_PER_CPU| DEFINE_PER_CPU| + static_assert| + # declaration primitives __typeof__\(| union| struct| @@ -5976,11 +5997,11 @@ sub process { ERROR("MULTISTATEMENT_MACRO_USE_DO_WHILE", "Macros starting with if should be enclosed by a do - while loop to avoid possible if/else logic defects\n" . "$herectx"); } elsif ($dstat =~ /;/) { - ERROR("MULTISTATEMENT_MACRO_USE_DO_WHILE", - "Macros with multiple statements should be enclosed in a do - while loop\n" . "$herectx"); + WARN("MULTISTATEMENT_MACRO_USE_DO_WHILE", + "Non-declarative macros with multiple statements should be enclosed in a do - while loop\n" . "$herectx\nBUT SEE:\n$DO_WHILE_0_ADVICE"); } else { ERROR("COMPLEX_MACRO", - "Macros with complex values should be enclosed in parentheses\n" . "$herectx"); + "Macros with complex values should be enclosed in parentheses\n" . "$herectx\nBUT SEE:\n$DO_WHILE_0_ADVICE"); } } |