linux-kernel - Re: [PATCH 1/1] checkpatch: recognise NOKPROBE_SYMBOL for blank line detection after function/struct/union/enum

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Message-ID: <e092f27243feeeec282ef8fdab57d8f9ee88a32d.camel@perches.com>
Date:   Fri, 20 Jan 2023 08:10:52 -0800
From:   Joe Perches <joe@...ches.com>
To:     Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Andy Whitcroft <apw@...onical.com>
Cc:     Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        linux-kernel@...r.kernel.org,
        kernel-janitors <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH 1/1] checkpatch: recognise NOKPROBE_SYMBOL for blank
 line detection after function/struct/union/enum

On Fri, 2023-01-20 at 12:46 +0100, Christian Borntraeger wrote:
> NOKPROBE_SYMBOL should be treated like EXPORT_SYMBOL to avoid
> false positives.
[]
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
> @@ -3995,6 +3995,7 @@ sub process {
>  		    $line =~ /^\+/ &&
>  		    !($line =~ /^\+\s*$/ ||
>  		      $line =~ /^\+\s*(?:EXPORT_SYMBOL|early_param)/ ||
> +		      $line =~ /^\+\s*NOKPROBE_SYMBOL/ ||
>  		      $line =~ /^\+\s*MODULE_/i ||
>  		      $line =~ /^\+\s*\#\s*(?:end|elif|else)/ ||
>  		      $line =~ /^\+[a-z_]*init/ ||

$ git grep -P -w -oh '\w*NOKPROBE_SYMBOL\w*' | sort | uniq -c
     60 _ASM_NOKPROBE_SYMBOL
      2 __NOKPROBE_SYMBOL
    304 NOKPROBE_SYMBOL

Any issue with these other variants? (it doesn't seem so)

btw: __NOKPROBE_SYMBOL has a ; at the end of its definition.

include/asm-generic/kprobes.h:# define __NOKPROBE_SYMBOL(fname)                         \
include/asm-generic/kprobes.h-static unsigned long __used                                       \
include/asm-generic/kprobes.h-  __section("_kprobe_blacklist")                          \
include/asm-generic/kprobes.h-  _kbl_addr_##fname = (unsigned long)fname;

And so there are extra ; uses after ever use of NOKPROBE_SYMBOL(foo);

$ git grep -w NOKPROBE_SYMBOL | grep ';' | wc -l
285

There are only 10 uses of NOKPROBE_SYMBOL(foo) without a semicolon

$ git grep -P '\bNOKPROBE_SYMBOL\s*\(\s*\w+\s*\)\s*(?:[^\;]|$)'
arch/arm/kernel/traps.c:NOKPROBE_SYMBOL(do_undefinstr)
arch/arm/probes/kprobes/opt-arm.c:NOKPROBE_SYMBOL(optimized_callback)
arch/arm64/kernel/kgdb.c:NOKPROBE_SYMBOL(kgdb_brk_fn)
arch/powerpc/mm/cacheflush.c:NOKPROBE_SYMBOL(flush_dcache_icache_phys)
arch/powerpc/platforms/82xx/pq2.c:NOKPROBE_SYMBOL(pq2_restart)
include/asm-generic/kprobes.h:# define NOKPROBE_SYMBOL(fname)   __NOKPROBE_SYMBOL(fname)
include/asm-generic/kprobes.h:# define NOKPROBE_SYMBOL(fname)
kernel/fail_function.c:NOKPROBE_SYMBOL(fei_kprobe_handler)
kernel/kprobes.c:NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
kernel/trace/trace_eprobe.c:NOKPROBE_SYMBOL(process_fetch_insn)
kernel/trace/trace_kprobe.c:NOKPROBE_SYMBOL(process_fetch_insn)
kernel/trace/trace_uprobe.c:NOKPROBE_SYMBOL(process_fetch_insn)

The actual uses with NOKPROBE_SYMBOL(foo) should likely have semicolons added
and the __NOKPROBE_SYMBOL definition should have the semicolon removed.