Re: [PATCH] checkpatch: fix a number of COMPLEX_MACRO false positives

[Vladimir Zapolskiy <vz@mleia.com>]

Hello Joe,

I'm adding Dan to Cc.

On 30.10.2015 01:52, Vladimir Zapolskiy wrote:
> On 30.10.2015 00:46, Joe Perches wrote:
>> On Thu, 2015-10-29 at 23:36 +0200, Vladimir Zapolskiy wrote:
>>> A simple search over the kernel souce displays a number of correctly
>>> defined multiline macro, which generally are used as an array element
>>> initializer:
>>>
>>> % find ../linux -type f | xargs grep -B1 -H '^[:space]*\[.*\\$'
>>>
>>> However checkpatch.pl unexpectedly complains about all these macro
>>> definitions:
>>>
>>> % ./scripts/checkpatch.pl --types COMPLEX_MACRO -f include/linux/perf/arm_pmu.h
>>>
>>> ERROR: Macros with complex values should be enclosed in parentheses
>>> +#define PERF_MAP_ALL_UNSUPPORTED					\
>>> +	 [0 ... PERF_COUNT_HW_MAX - 1] = HW_OP_UNSUPPORTED
>>>
>>> The change intends to fix this type of false positives by flattening
>>> only array members and skipping array element designators.
>>>
>>> Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
>>> ---
>>>  scripts/checkpatch.pl | 5 +++--
>>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>>> index f2a1131..3882893 100755
>>> --- a/scripts/checkpatch.pl
>>> +++ b/scripts/checkpatch.pl
>>> @@ -4526,7 +4526,7 @@ sub process {
>>>  			# Flatten any parentheses and braces
>>>  			while ($dstat =~ s/\([^\(\)]*\)/1/ ||
>>>  			       $dstat =~ s/\{[^\{\}]*\}/1/ ||
>>> -			       $dstat =~ s/\[[^\[\]]*\]/1/)
>>> +			       $dstat =~ s/.\[[^\[\]]*\]/1/)
>>
>> Perhaps the . before the [ might be a bit broad.
> 
> At this point preceding spaces and parentheses are removed, probably any
> alphanumeric symbol should fit here.
> 
> OTOH I believe in correct C code here before \[ symbol you may find only
> an alphanumeric symbol or ^, so I don't expect any false negatives, if .
> is used above.
> 

I tested this version (COMPLEX_MACRO only) with . symbol over all .c and
.h files in the kernel (commit ce5c2d2c256a4) and the change fixes 230
false positives, see the list below in format $file:$lineno.

No new false negatives are introduced, so according to my test . is okay
here to have.

Please also note that the problem is quite old and it emerged earlier,
e.g. see http://permalink.gmane.org/gmane.linux.ports.arm.kernel/451646 etc.

>> I'm not sure there's a great way to handle this.
>>
>> Andy?
>>>  			{
>>>  			}
>>>  
>>> @@ -4546,7 +4546,8 @@ sub process {
>>>  				union|
>>>  				struct|
>>>  				\.$Ident\s*=\s*|
>>> -				^\"|\"$
>>> +				^\"|\"$|
>>> +				^\[
>>>  			}x;
>>>  			#print "REST<$rest> dstat<$dstat> ctx<$ctx>\n";
>>>  			if ($dstat ne '' &&

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  arch/arm64/kernel/smp.c:624
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  arch/arm64/kernel/sys.c:46
  arch/arm/kernel/smp.c:473
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  arch/arm/mach-davinci/mux.h:29
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  arch/arm/mach-imx/devices/platform-imx-uart.c:22
  arch/arm/mach-imx/devices/platform-mxc-mmc.c:23
  arch/arm/mach-imx/devices/platform-sdhci-esdhc-imx.c:22
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  arch/blackfin/mach-bf527/boards/ezkit.c:513
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  arch/blackfin/mach-bf533/boards/stamp.c:612
  arch/blackfin/mach-bf537/boards/stamp.c:2546
  arch/blackfin/mach-bf537/boards/stamp.c:2564
  arch/blackfin/mach-bf548/boards/ezkit.c:1834
  arch/blackfin/mach-bf548/boards/ezkit.c:1860
  arch/c6x/kernel/sys_c6x.c:51
  arch/h8300/kernel/syscalls.c:6
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  arch/mips/include/asm/mach-bcm63xx/bcm63xx_cpu.h:551
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  Documentation/networking/timestamping/hwtstamp_config.c:46
  Documentation/networking/timestamping/hwtstamp_config.c:55
  drivers/gpu/drm/amd/amdkfd/kfd_chardev.c:871
  drivers/gpu/drm/drm_ioctl.c:513
  drivers/gpu/drm/drm_modes.c:1020
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  drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c:97
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  drivers/media/v4l2-core/v4l2-ioctl.c:2412
  drivers/mfd/asic3.c:55
  drivers/mfd/axp20x.c:248
  drivers/mfd/db8500-prcmu.c:279
  drivers/mfd/db8500-prcmu.c:333
  drivers/mfd/db8500-prcmu.c:467
  drivers/mfd/max8997-irq.c:68
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  drivers/net/wireless/iwlwifi/mvm/rs.c:86
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  net/core/neighbour.c:3026
  net/mac80211/debugfs.c:95
  net/mac80211/rc80211_minstrel_ht.c:129
  net/mac80211/rc80211_minstrel_ht.c:54
  net/mac80211/rc80211_minstrel_ht.c:82
  net/sunrpc/auth_gss/gss_rpc_upcall.c:55
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--
With best wishes,
Vladimir