On Fri, 31 May 2019, Petr Mladek wrote:
> WARN_ONCE() in the generic save_stack_trace_tsk_reliable() is superfluous.
>
> The information is passed also via the return value. The only current
> user klp_check_stack() writes its own warning when the reliable stack
> traces are not supported. Other eventual users might want its own error
> handling as well.
>
> Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
> Acked-by: Miroslav Benes <mbenes@xxxxxxx>
> Reviewed-by: Kamalesh Babulal <kamalesh@xxxxxxxxxxxxxxxxxx>
> ---
> kernel/stacktrace.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
> index 5667f1da3ede..8d088408928d 100644
> --- a/kernel/stacktrace.c
> +++ b/kernel/stacktrace.c
> @@ -259,7 +259,6 @@ __weak int
> save_stack_trace_tsk_reliable(struct task_struct *tsk,
> struct stack_trace *trace)
> {
> - WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
> return -ENOSYS;
> }
Do we even need the weak function now after Thomas' changes to
kernel/stacktrace.c?
- livepatch is the only user and it calls stack_trace_save_tsk_reliable()
- x86 defines CONFIG_ARCH_STACKWALK and CONFIG_HAVE_RELIABLE_STACKTRACE,
so it has stack_trace_save_tsk_reliable() implemented and it calls
arch_stack_walk_reliable()
- powerpc defines CONFIG_HAVE_RELIABLE_STACKTRACE and does not have
CONFIG_ARCH_STACKWALK. It also has stack_trace_save_tsk_reliable()
implemented and it calls save_stack_trace_tsk_reliable(), which is
implemented in arch/powerpc/
- all other archs do not have CONFIG_HAVE_RELIABLE_STACKTRACE and there is
stack_trace_save_tsk_reliable() returning ENOSYS for these cases in
include/linux/stacktrace.c
Miroslav
