From: Peter Zijlstra <peterz@infradead.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Adrian Hunter <adrian.hunter@intel.com>,
Tobias Klauser <tklauser@distanz.ch>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Chengming Zhou <zhouchengming@bytedance.com>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ftrace: shut up -Wcast-function-type warning for ftrace_ops_no_ops
Date: Tue, 23 Mar 2021 08:39:08 +0100 [thread overview]
Message-ID: <YFmbHI4hnKg5UH2M@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210322215006.1028517-1-arnd@kernel.org>
On Mon, Mar 22, 2021 at 10:49:58PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> With 'make W=1', gcc warns about casts between incompatible function
> types:
>
> kernel/trace/ftrace.c:128:31: error: cast between incompatible function types from 'void (*)(long unsigned int, long unsigned int)' to 'void (*)(long unsigned int, long unsigned int, struct ftrace_ops *, struct ftrace_regs *)' [-Werror=cast-function-type]
> 128 | #define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
> | ^
>
> As the commet here explains, this one was intentional, so shut up the
> warning harder by using a double cast.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> kernel/trace/ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 4d8e35575549..d8fc87a17421 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -125,7 +125,7 @@ static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
> #else
> /* See comment below, where ftrace_ops_list_func is defined */
> static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
> -#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
> +#define ftrace_ops_list_func ((ftrace_func_t)(void *)ftrace_ops_no_ops)
So now we're making perfectly fine code worse, because GCC is stupid?
Please just kill the warning, like we do with so many other warnings.
It's broken!
next prev parent reply other threads:[~2021-03-23 7:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 21:49 [PATCH] ftrace: shut up -Wcast-function-type warning for ftrace_ops_no_ops Arnd Bergmann
2021-03-22 22:00 ` Steven Rostedt
2021-03-23 7:39 ` Peter Zijlstra [this message]
2021-03-23 12:57 ` Steven Rostedt
2021-03-23 15:25 ` Peter Zijlstra
2021-03-23 16:05 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YFmbHI4hnKg5UH2M@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=adrian.hunter@intel.com \
--cc=arnd@arndb.de \
--cc=arnd@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=paulmck@kernel.org \
--cc=richard.weiyang@linux.alibaba.com \
--cc=rostedt@goodmis.org \
--cc=tklauser@distanz.ch \
--cc=zhouchengming@bytedance.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).