Re: [PATCH bpf-next v2 02/21] bpf: Drop unnecessary ftrace_location() in register/unregister/modify_fentry_multi()

[Jiri Olsa]

On Mon, Oct 12, 2026 at 11:40:04PM +0800, Leon Hwang wrote:
> Since 'tr->ip' is already a 'ftrace_location()'-ed IP in
> bpf_trampoline_lookup(), it is unnecessary to call ftrace_location() again
> in register/unregister/modify_fentry_multi().
> 
> No functional changes intended.
> 
> Signed-off-by: Leon Hwang <leon.hwang@xxxxxxxxx>

Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>

jirka

> ---
>  kernel/bpf/trampoline.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
> index 17f2a8133f61..21d460866dfe 100644
> --- a/kernel/bpf/trampoline.c
> +++ b/kernel/bpf/trampoline.c
> @@ -1629,8 +1629,8 @@ static void ftrace_hash_add(struct ftrace_hash *hash, struct ftrace_func_entry *
>  static int register_fentry_multi(struct bpf_trampoline *tr, struct bpf_tramp_image *im, void *ptr)
>  {
>  	unsigned long addr = (unsigned long) im->image;
> -	unsigned long ip = ftrace_location(tr->ip);
>  	struct bpf_tracing_multi_data *data = ptr;
> +	unsigned long ip = tr->ip;
>  
>  	/*
>  	 * Different BTF ids get different trampolines, but they can still
> @@ -1651,13 +1651,12 @@ static int register_fentry_multi(struct bpf_trampoline *tr, struct bpf_tramp_ima
>  static int unregister_fentry_multi(struct bpf_trampoline *tr, u32 orig_flags, void *ptr)
>  {
>  	unsigned long addr = (unsigned long) tr->cur_image->image;
> -	unsigned long ip = ftrace_location(tr->ip);
>  	struct bpf_tracing_multi_data *data = ptr;
>  
>  	if (bpf_trampoline_use_jmp(tr->flags))
>  		addr = ftrace_jmp_set(addr);
>  
> -	ftrace_hash_add(data->unreg, data->entry, ip, addr);
> +	ftrace_hash_add(data->unreg, data->entry, tr->ip, addr);
>  	tr->cur_image = NULL;
>  	return 0;
>  }
> @@ -1666,13 +1665,12 @@ static int modify_fentry_multi(struct bpf_trampoline *tr, u32 orig_flags, struct
>  			       bool lock_direct_mutex, void *ptr)
>  {
>  	unsigned long addr = (unsigned long) im->image;
> -	unsigned long ip = ftrace_location(tr->ip);
>  	struct bpf_tracing_multi_data *data = ptr;
>  
>  	if (bpf_trampoline_use_jmp(tr->flags))
>  		addr = ftrace_jmp_set(addr);
>  
> -	ftrace_hash_add(data->modify, data->entry, ip, addr);
> +	ftrace_hash_add(data->modify, data->entry, tr->ip, addr);
>  	tr->cur_image = im;
>  	return 0;
>  }
> -- 
> 2.55.0
>