Nathan Lynch via B4 Relay <devnull+nathanl.linux.ibm....@kernel.org>
writes:
> From: Nathan Lynch <nath...@linux.ibm.com>
>
> If the function descriptor has a populated lock member, then callers
> are required to hold it across calls. Now that the firmware activation
> sequence is appropriately guarded, we can warn when the requirement
> isn't satisfied.
>
> __do_enter_rtas_trace() gets reorganized a bit as a result of
> performing the function descriptor lookup unconditionally now.
>
Reviewed-by: Aneesh Kumar K.V (IBM) <aneesh.ku...@kernel.org>
> Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
> ---
> arch/powerpc/kernel/rtas.c | 21 +++++++++------------
> 1 file changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index e38ba05ad613..deb6289fcf9c 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -685,28 +685,25 @@ static void __do_enter_rtas(struct rtas_args *args)
>
> static void __do_enter_rtas_trace(struct rtas_args *args)
> {
> - const char *name = NULL;
> + struct rtas_function *func =
> rtas_token_to_function(be32_to_cpu(args->token));
>
> - if (args == &rtas_args)
> - lockdep_assert_held(&rtas_lock);
> /*
> - * If the tracepoints that consume the function name aren't
> - * active, avoid the lookup.
> + * If there is a per-function lock, it must be held by the
> + * caller.
> */
> - if ((trace_rtas_input_enabled() || trace_rtas_output_enabled())) {
> - const s32 token = be32_to_cpu(args->token);
> - const struct rtas_function *func =
> rtas_token_to_function(token);
> + if (func->lock)
> + WARN_ON(!mutex_is_locked(func->lock));
>
> - name = func->name;
> - }
> + if (args == &rtas_args)
> + lockdep_assert_held(&rtas_lock);
>
> - trace_rtas_input(args, name);
> + trace_rtas_input(args, func->name);
> trace_rtas_ll_entry(args);
>
> __do_enter_rtas(args);
>
> trace_rtas_ll_exit(args);
> - trace_rtas_output(args, name);
> + trace_rtas_output(args, func->name);
> }
>
> static void do_enter_rtas(struct rtas_args *args)
>
> --
> 2.41.0
