Re: [PATCH] tracing: always provide a prototype for tracing_alloc_snapshot()

[Google]

On Tue, 31 Mar 2026 10:20:01 +0200
Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx> wrote:

> The tracing_alloc_snapshot() symbol is always exported even with
> !CONFIG_TRACER_SNAPSHOT so the prototype too must be always visible or
> we'll see the following warning:
> 
> kernel/trace/trace.c:820:5: warning: no previous prototype for ‘tracing_alloc_snapshot’ [-Wmissing-prototypes]
>   820 | int tracing_alloc_snapshot(void)
>       |     ^~~~~~~~~~~~~~~~~~~~~~
> 
> Fixes: bade44fe5462 ("tracing: Move snapshot code out of trace.c and into trace_snapshot.c")
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>

Good catch!

Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Thanks!

> ---
>  kernel/trace/trace.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 6abd9e16ef21..e8612b8b0a34 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -2275,6 +2275,8 @@ static inline void __init trace_event_init(void) { }
>  static inline void trace_event_update_all(struct trace_eval_map **map, int len) { }
>  #endif
>  
> +int tracing_alloc_snapshot(void);
> +
>  #ifdef CONFIG_TRACER_SNAPSHOT
>  extern const struct file_operations snapshot_fops;
>  extern const struct file_operations snapshot_raw_fops;
> @@ -2282,7 +2284,6 @@ extern const struct file_operations snapshot_raw_fops;
>  /* Used when creating instances */
>  int trace_allocate_snapshot(struct trace_array *tr, int size);
>  
> -int tracing_alloc_snapshot(void);
>  void tracing_snapshot_cond(struct trace_array *tr, void *cond_data);
>  int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update);
>  int tracing_snapshot_cond_disable(struct trace_array *tr);
> -- 
> 2.47.3
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>