Re: [PATCH] fgraph: Remove unused FGRAPH_MAX_INDEX

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

On Sun,  6 Sep 2026 06:19:22 +0900
Donggeun Yoo <donggeunyoo.kernel@gmail.com> wrote:

> FGRAPH_MAX_INDEX has no user, and it expands to FGRAPH_INDEX_SIZE and
> FGRAPH_RET_INDEX, neither of which is defined anywhere in the tree. It
> was added in that form by commit 91c46b0aa917 ("function_graph:
> Implement fgraph_reserve_data() and fgraph_retrieve_data()"), which
> introduced the current data word layout under new names, so anything
> referencing it would have failed to build ever since.
> 
> Remove it.
>

Looks good to me.

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

Thanks!
 
> Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
> ---
> Found while reading the shadow stack word layout. The macro is dead in
> both senses: nothing references it, and it could not be used as it is.
> 
> Compile-tested only, with CONFIG_FUNCTION_GRAPH_TRACER=y and
> CONFIG_DYNAMIC_FTRACE=y. Removing an unreferenced macro cannot change
> generated code, so there is nothing to test at run time.
> 
>  kernel/trace/fgraph.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 40d373d65f9b..ed455b53513b 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -143,9 +143,6 @@ enum {
>  #define FGRAPH_DATA_INDEX_MASK	GENMASK(FGRAPH_DATA_INDEX_BITS - 1, 0)
>  #define FGRAPH_DATA_INDEX_SHIFT	(FGRAPH_DATA_SHIFT + FGRAPH_DATA_BITS)
>  
> -#define FGRAPH_MAX_INDEX	\
> -	((FGRAPH_INDEX_SIZE << FGRAPH_DATA_BITS) + FGRAPH_RET_INDEX)
> -
>  #define FGRAPH_ARRAY_SIZE	FGRAPH_INDEX_BITS
>  
>  /*
> -- 
> 2.53.0
> 


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