Messages in this thread | | | Subject | Re: [PATCH RFC] checkpatch: fix multi-statement macro checks | From | Joe Perches <> | Date | Thu, 01 Oct 2020 07:38:12 -0700 |
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On Thu, 2020-10-01 at 19:44 +0530, Dwaipayan Ray wrote: > On Thu, Oct 1, 2020 at 7:12 PM Joe Perches <joe@perches.com> wrote: > > On Thu, 2020-10-01 at 18:57 +0530, Dwaipayan Ray wrote: > > > On Thu, Oct 1, 2020 at 6:47 PM Joe Perches <joe@perches.com> wrote: > > > > On Thu, 2020-10-01 at 16:03 +0530, Dwaipayan Ray wrote: > > > > > Checkpatch.pl doesn't have a check for excluding while (...) {...} > > > > > blocks from MULTISTATEMENT_MACRO_USE_DO_WHILE error. > > > > > > > > > > For example, running checkpatch.pl on the file mm/access.c in the > > > > > kernel generates the following error: > > > > > > > > > > ERROR: Macros with complex values should be enclosed in parentheses > > > > > +#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \ > > > > > + while (len >= sizeof(type)) { \ > > > > > + __get_kernel_nofault(dst, src, type, err_label); \ > > > > > + dst += sizeof(type); \ > > > > > + src += sizeof(type); \ > > > > > + len -= sizeof(type); \ > > > > > + } > > > > > > > > > > The error is misleading for this case. Enclosing it in parantheses > > > > > doesn't make any sense. > > > > > > > > OK > > > > > > > > > Checkpatch already has an exception list for such common macro types. > > > > > Added a new exception for while (...) {...} style blocks to the same. > > > > > This effectively fixed the wrong error message. > > > > [] > > > > > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl > > > > [] > > > > > @@ -5342,6 +5342,7 @@ sub process { > > > > > $dstat !~ /^\.$Ident\s*=/ && # .foo = > > > > > $dstat !~ /^(?:\#\s*$Ident|\#\s*$Constant)\s*$/ && # stringification #foo > > > > > $dstat !~ /^do\s*$Constant\s*while\s*$Constant;?$/ && # do {...} while (...); // do {...} while (...) > > > > > + $dstat !~ /^while\s*$Constant\s*$Constant\s*$/ && # while (...) {...} > > > > Note the \s* > > ^ > > > > > > Did you try to output $dstat for some matching cases? > > > > What was the $dstat value for the cases you tried? > > > > > > > > > > > Hi, > > > I did check $dstat values. > > > > > > For example on file mm/maccess.c, there were two such macros: > > > > > > Case 1: > > > > > > $ctx: > > > +#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label) \ > > > + while (len >= sizeof(type)) { \ > > > + __get_kernel_nofault(dst, src, type, err_label); \ > > > + dst += sizeof(type); \ > > > + src += sizeof(type); \ > > > + len -= sizeof(type); \ > > > + } > > > > > > $dstat: > > > while 1 1 > > > > And perhaps this test should use \s+ instead. > > What is $dstat with a #define like: > > > > #define foo(bar,baz)while(bar){bar--;baz++;} > > > > (no spaces anywhere bot the required one after define > > > > In this case, $dstat is: while11 > > So, if \s+ is used, it won't match with this. I ran checkpatch > on it and some other condition seems to match, so it is > excluded from the error. > > However, if the macro is like: > > #define foo(bar,baz)while(bar) {bar--;baz++;} > (one space after condition) > > $dstat is: while1 1 > (space after first 1) > and the same error is again emitted. > > So I think \s* works better since there can be > 0 or more whitespaces between them.
All I'm trying to point out to you is that $Constant\s*$Constant isn't a proper test as the first $Constant will pull the test entire sequence of digits and the second $Constant will not be met.
It may take some conversion of the collapsing of the dstat block to work appropriately
# Flatten any parentheses and braces while ($dstat =~ s/\([^\(\)]*\)/1/ || $dstat =~ s/\{[^\{\}]*\}/1/ || $dstat =~ s/.\[[^\[\]]*\]/1/) { }
Maybe the /1/ should be / 1 / but I didn't look to see what happens to the exclusion tests below that.
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