Re: [Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
> +# nested likely/unlikely calls > + if ($line =~ > /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { > + WARN("LIKELY_MISUSE", … >> \b(?:un)?likely\s* > > This pair of brackets is required to match "unlikely" > and it's optional in order to match "likely". I agree also to this view if you refer to the shortened regular expression here. But I got an other development opinion for an extra pair of non-capturing parentheses at the front (from the version which you suggested). Regards, Markus ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
Re: [Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
+# nested likely/unlikely calls + if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { + WARN("LIKELY_MISUSE", How do you think about to use the specification “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)” in this regular expression? Regards, Markus ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
Re: [Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
>>> +# nested likely/unlikely calls >>> + if ($line =~ >>> /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { >>> + WARN("LIKELY_MISUSE", >> >> How do you think about to use the specification >> “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)” >> in this regular expression? … >IS_ERR >(?:_ <- Another atomic group just to show that '_' is a common prefix? Yes. - I hope that this specification detail can help a bit. >Usually, Perl interpreter is very good at optimizing such things. Would you like to help this software component by omitting a pair of non-capturing parentheses at the beginning? \b(?:un)?likely\s* Regards, Markus ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
Re: [Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
On 31.08.2019 19:45, Markus Elfring wrote: +# nested likely/unlikely calls + if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { + WARN("LIKELY_MISUSE", >>> >>> How do you think about to use the specification >>> “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)” >>> in this regular expression? > … >>IS_ERR >>(?:_ <- Another atomic group just to show that '_' is a common prefix? > > Yes. - I hope that this specification detail can help a bit. I'm not sure that another pair of brackets for a single char worth it. >>Usually, Perl interpreter is very good at optimizing such things. The interpreter optimizes it internally: echo 'IS_ERR_OR_NULL' | perl -Mre=debug -ne '/IS_ERR(?:_OR_NULL|_VALUE)?/ && print' Compiling REx "IS_ERR(?:_OR_NULL|_VALUE)?" Final program: 1: EXACT (4) 4: CURLYX[0]{0,1} (16) 6: EXACT <_> (8) <-- common prefix 8: TRIE-EXACT[OV] (15) ... > > Would you like to help this software component by omitting a pair of > non-capturing parentheses at the beginning? > > \b(?:un)?likely\s* This pair of brackets is required to match "unlikely" and it's optional in order to match "likely". Regards, Denis ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
Re: [Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
On 31.08.2019 12:15, Markus Elfring wrote: >> +# nested likely/unlikely calls >> + if ($line =~ >> /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { >> + WARN("LIKELY_MISUSE", > > How do you think about to use the specification > “(?:IS_ERR(?:_(?:OR_NULL|VALUE))?|WARN)” > in this regular expression? Hmm, (?: <- Catch group is required here, since it is used in diagnostic message, see $1 IS_ERR (?:_ <- Another atomic group just to show that '_' is a common prefix? I'm not sure about this. Usually, Perl interpreter is very good at optimizing such things. You could see this optimization if you run perl with -Mre=debug. (?:OR_NULL|VALUE))?|WARN) Regards, Denis ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
[Xen-devel] [PATCH v3 01/11] checkpatch: check for nested (un)?likely() calls
IS_ERR(), IS_ERR_OR_NULL(), IS_ERR_VALUE() and WARN*() already contain unlikely() optimization internally. Thus, there is no point in calling these functions and defines under likely()/unlikely(). This check is based on the coccinelle rule developed by Enrico Weigelt https://lore.kernel.org/lkml/1559767582-11081-1-git-send-email-i...@metux.net/ Signed-off-by: Denis Efremov Cc: Joe Perches Cc: Andrew Morton Cc: Andy Whitcroft --- scripts/checkpatch.pl | 6 ++ 1 file changed, 6 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 93a7edfe0f05..56969ce06df4 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6480,6 +6480,12 @@ sub process { "Using $1 should generally have parentheses around the comparison\n" . $herecurr); } +# nested likely/unlikely calls + if ($line =~ /\b(?:(?:un)?likely)\s*\(\s*!?\s*(IS_ERR(?:_OR_NULL|_VALUE)?|WARN)/) { + WARN("LIKELY_MISUSE", +"nested (un)?likely() calls, $1 already uses unlikely() internally\n" . $herecurr); + } + # whine mightly about in_atomic if ($line =~ /\bin_atomic\s*\(/) { if ($realfile =~ m@^drivers/@) { -- 2.21.0 ___ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel