From: Stephen Brennan <stephen.s.brennan@oracle.com>
To: kernel test robot <lkp@intel.com>
Cc: 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: Thu, 16 May 2024 13:50:31 -0700 [thread overview]
Message-ID: <87eda1pjl4.fsf@oracle.com> (raw)
In-Reply-To: <202405170340.eyEMhYvc-lkp@intel.com>
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.
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
next prev parent reply other threads:[~2024-05-16 20:50 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 [this message]
2024-05-17 16:40 ` Nathan Chancellor
2024-05-18 14:50 ` Masami Hiramatsu
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