From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: kernel test robot <lkp@intel.com>,
llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
"Steven Rostedt (Google)" <rostedt@goodmis.org>
Subject: Re: [trace:probes/for-next 17/17] kernel/kprobes.c:1141:24: error: a function declaration without a prototype is deprecated in all versions of C
Date: Sat, 18 May 2024 23:50:59 +0900 [thread overview]
Message-ID: <20240518235059.3c3a0065a9980e8eb09f68b4@kernel.org> (raw)
In-Reply-To: <87eda1pjl4.fsf@oracle.com>
On Thu, 16 May 2024 13:50:31 -0700
Stephen Brennan <stephen.s.brennan@oracle.com> wrote:
> kernel test robot <lkp@intel.com> writes:
> > tree: git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace probes/for-next
> > head: 1a7d0890dd4a502a202aaec792a6c04e6e049547
> > commit: 1a7d0890dd4a502a202aaec792a6c04e6e049547 [17/17] kprobe/ftrace: bail out if ftrace was killed
> > config: s390-defconfig (https://download.01.org/0day-ci/archive/20240517/202405170340.eyEMhYvc-lkp@intel.com/config)
> > compiler: clang version 19.0.0git (https://github.com/llvm/llvm-project d3455f4ddd16811401fa153298fadd2f59f6914e)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240517/202405170340.eyEMhYvc-lkp@intel.com/reproduce)
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202405170340.eyEMhYvc-lkp@intel.com/
> >
> > All errors (new ones prefixed by >>):
> >
> > In file included from kernel/kprobes.c:23:
> > In file included from include/linux/kprobes.h:28:
> > In file included from include/linux/ftrace.h:13:
> > In file included from include/linux/kallsyms.h:13:
> > In file included from include/linux/mm.h:2210:
> > include/linux/vmstat.h:508:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
> > 508 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~ ^
> > 509 | item];
> > | ~~~~
> > include/linux/vmstat.h:515:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
> > 515 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~ ^
> > 516 | NR_VM_NUMA_EVENT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~~
> > include/linux/vmstat.h:522:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
> > 522 | return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
> > | ~~~~~~~~~~~ ^ ~~~
> > include/linux/vmstat.h:527:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
> > 527 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~ ^
> > 528 | NR_VM_NUMA_EVENT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~~
> > include/linux/vmstat.h:536:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
> > 536 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~ ^
> > 537 | NR_VM_NUMA_EVENT_ITEMS +
> > | ~~~~~~~~~~~~~~~~~~~~~~
> >>> kernel/kprobes.c:1141:24: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
> > 1141 | void kprobe_ftrace_kill()
> > | ^
> > | void
> > 5 warnings and 1 error generated.
>
> This certainly reads as an error in my patch. I tried to carefully
> include three declarations:
>
> 1. CONFIG_KPROBES && CONFIG_KPROBES_ON_FTRACE (the extern decl)
> 2. CONFIG_KPROBES && !CONFIG_KPROBES_ON_FTRACE (a static inline)
> 3. !CONFIG_KPROBES (a static inline)
>
> To double check, I actually used an ifdef visualizer[1] (written by a
> coworker) and as far as I can see, I did this correctly...
>
> When I pull probes/for-next and the 0day compiler configuration, I do
> reproduce the build error.
>
> However, I'm not 100% confident that this is a real error. I ran the
> build with make V=1, and found the clang build command to build the
> kernel/kprobes.c command. I replaced the "-c -o kernel/kprobes.o" with
> "-E", so that I could simply browse the preprocessed source code. I cd
> into the build directory and do:
>
> $extremely_long_clang_command ... -E $srcdir/kernel/kprobes.o \
> | grep kprobe_ftrace_kill
> extern void kprobe_ftrace_kill(void);
> void kprobe_ftrace_kill()
>
> ---
>
> When I do a GCC cross compile (s390x-linux-gnu-gcc) using the same
> configuration file, with "W=1 V=1" I do see:
>
> /home/stepbren/repos/linux-upstream/kernel/kprobes.c: In function ‘kprobe_ftrace_kill’:
> /home/stepbren/repos/linux-upstream/kernel/kprobes.c:1141:6: warning: old-style function definition [-Wold-style-definition]
> 1141 | void kprobe_ftrace_kill()
> | ^~~~~~~~~~~~~~~~~~
>
> I'm guessing that what's happening here is that Clang is categorizing
> the old-style declaration as a different function for which there was no
> prior declaration. When I add the "void" here, the clang error goes
> away.
>
> In any case, the warning is right, and I should have used the correct
> declaration here. The below patch will shut this up. If there's any
> possibility of improving the error message clang gives us here, it would
> be appreciated though.
>
> Masami, would you like me to send this to the list, or do you just want
> to fix up the commit? My apologies for this, I should have run the "make
> W=1" prior to submission.
Sorry, that is my mistake to missed the issue. Linus alreay fixed the
error (I confirmed).
I also forgot to run W=1 build. Let me fix my process.
Thank you,
>
> Thanks,
> Stephen
>
> From 324849fd366b8d2d4367ed2cd6f74621099439e1 Mon Sep 17 00:00:00 2001
> From: Stephen Brennan <stephen.s.brennan@oracle.com>
> Date: Thu, 16 May 2024 13:48:32 -0700
> Subject: [PATCH] kprobes/ftrace: fix old-style function declaration
>
> Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
> ---
> kernel/kprobes.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 166ebf81dc450..4f917bdad1e11 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1138,7 +1138,7 @@ static int disarm_kprobe_ftrace(struct kprobe *p)
> ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
> }
>
> -void kprobe_ftrace_kill()
> +void kprobe_ftrace_kill(void)
> {
> kprobe_ftrace_disabled = true;
> }
> --
> 2.43.0
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
prev parent reply other threads:[~2024-05-18 14:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-16 19:15 [trace:probes/for-next 17/17] kernel/kprobes.c:1141:24: error: a function declaration without a prototype is deprecated in all versions of C kernel test robot
2024-05-16 20:50 ` Stephen Brennan
2024-05-17 16:40 ` Nathan Chancellor
2024-05-18 14:50 ` Masami Hiramatsu [this message]
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