Re: [PATCH RFC 03/10] perf: Simplify get_perf_callchain() user logic

[Namhyung Kim]

On Wed, Nov 8, 2023 at 4:44 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
>
> Simplify the get_perf_callchain() user logic a bit.  task_pt_regs()
> should never be NULL.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Thanks,
Namhyung

> ---
>  kernel/events/callchain.c | 16 +++++++---------
>  1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
> index aa5f9d11c28d..2bee8b6fda0e 100644
> --- a/kernel/events/callchain.c
> +++ b/kernel/events/callchain.c
> @@ -202,20 +202,18 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
>
>         if (user) {
>                 if (!user_mode(regs)) {
> -                       if  (current->mm)
> -                               regs = task_pt_regs(current);
> -                       else
> -                               regs = NULL;
> +                       if (!current->mm)
> +                               goto exit_put;
> +                       regs = task_pt_regs(current);
>                 }
>
> -               if (regs) {
> -                       if (add_mark)
> -                               perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
> +               if (add_mark)
> +                       perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
>
> -                       perf_callchain_user(&ctx, regs);
> -               }
> +               perf_callchain_user(&ctx, regs);
>         }
>
> +exit_put:
>         put_callchain_entry(rctx);
>
>         return entry;
> --
> 2.41.0
>