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
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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
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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
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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
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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
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[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
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