linux-kernel - Re: [for-next PATCH v2] tracing: wprobe: Fix to use IS_ERR

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Message-ID: <6198553.lOV4Wx5bFT@7950hx>
Date: Tue, 07 Oct 2025 11:12:18 +0800
From: Menglong Dong <menglong.dong@...ux.dev>
To: Steven Rostedt <rostedt@...dmis.org>,
 "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Mark Brown <broonie@...nel.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Menglong Dong <menglong8.dong@...il.com>,
 Thorsten Blum <thorsten.blum@...ux.dev>,
 Masami Hiramatsu <mhiramat@...nel.org>, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Subject:
 Re: [for-next PATCH v2] tracing: wprobe: Fix to use IS_ERR_PCPU() for per-cpu
 pointer

On 2025/10/7 09:03, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> Since wprobe uses IS_ERR() for per-cpu pointer, it failed to build.
> 
> /tmp/next/build/kernel/trace/trace_wprobe.c: In function '__register_trace_wprobe':
> /tmp/next/build/kernel/trace/trace_wprobe.c:176:20: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
>   176 |         if (IS_ERR((void * __force)tw->bp_event)) {
>       |                    ^
> /tmp/next/build/kernel/trace/trace_wprobe.c:177:35: error: cast to generic address space pointer from disjoint '__seg_gs' address space pointer [-Werror]
>   177 |                 int ret = PTR_ERR((void * __force)tw->bp_event);
>       |                                   ^
> 
> Use IS_ERR_PCPU() instead.
> 
> Reported-by: Mark Brown <broonie@...nel.org>
> Closes: https://lore.kernel.org/all/aN6fTmAjD7-SJsw2@sirena.org.uk/
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> ---
>  - Confirmed that `make allmodconfig && make` passed on x86_64 and arm64.
>  Changes in v2:
>  - Remove unneeded casting.
>  - Use PTR_ERR_PCPU() too.
> ---
>  kernel/trace/trace_wprobe.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c
> index 4b00a8e917c1..98605b207f43 100644
> --- a/kernel/trace/trace_wprobe.c
> +++ b/kernel/trace/trace_wprobe.c
> @@ -173,8 +173,8 @@ static int __register_trace_wprobe(struct trace_wprobe *tw)
>  	attr.bp_type = tw->type;
>  
>  	tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
> -	if (IS_ERR((void * __force)tw->bp_event)) {
> -		int ret = PTR_ERR((void * __force)tw->bp_event);
> +	if (IS_ERR_PCPU(tw->bp_event)) {
> +		int ret = PTR_ERR_PCPU(tw->bp_event);

This version LGTM.

Reviewed-by: Menglong Dong <menglong8.dong@...il.com>

>  
>  		tw->bp_event = NULL;
>  		return ret;
> 
> 
>