Re: [PATCH v2] rethook: Remove warning messages printed for finding return address of a frame.

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Mon,  8 Apr 2024 10:51:40 -0700
Kui-Feng Lee <thinker.li@gmail.com> wrote:

> The function rethook_find_ret_addr() prints a warning message and returns 0
> when the target task is running and is not the "current" task in order to
> prevent the incorrect return address, although it still may return an
> incorrect address.
> 
> However, the warning message turns into noise when BPF profiling programs
> call bpf_get_task_stack() on running tasks in a firm with a large number of
> hosts.
> 
> The callers should be aware and willing to take the risk of receiving an
> incorrect return address from a task that is currently running other than
> the "current" one. A warning is not needed here as the callers are intent
> on it.
> 

OK, looks good to me. Let me pick it to probes/for-next. Thanks!

> Acked-by: Andrii Nakryiko <andrii@kernel.org>
> Acked-by: John Fastabend <john.fastabend@gmail.com>
> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
> 
> ---
> Changes from v1:
> 
>  - Rephrased the commit log.
> 
>    - Removed the confusing last part of the first paragraph.
> 
>    - Removed "frequently" from the 2nd paragraph, replaced by "a firm with
>      a large number of hosts".
> 
> v1: https://lore.kernel.org/all/20240401191621.758056-1-thinker.li@gmail.com/
> ---
>  kernel/trace/rethook.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> index fa03094e9e69..4297a132a7ae 100644
> --- a/kernel/trace/rethook.c
> +++ b/kernel/trace/rethook.c
> @@ -248,7 +248,7 @@ unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame
>  	if (WARN_ON_ONCE(!cur))
>  		return 0;
>  
> -	if (WARN_ON_ONCE(tsk != current && task_is_running(tsk)))
> +	if (tsk != current && task_is_running(tsk))
>  		return 0;
>  
>  	do {
> -- 
> 2.34.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>