Bug 1824812

Description of problem:

Block layer update bug 1798919 adds iocost_ioc_vrate_adj trace point.
include/trace/events/iocost.h

TRACE_EVENT(iocost_ioc_vrate_adj,
        TP_PROTO(struct ioc *ioc, u64 new_vrate, u32 (*missed_ppm)[2],

It looks like the stap translate does not like the pointer to array as
parameter. I'm not sure if this needs to be fixed on stap side or the trace event should use different interface(maybe just u32 *missed_ppm)


Version-Release number of selected component (if applicable):
rhel8.3 kernel with patches for bug 1798919
Scratch build kernel-4.18.0-193.9.el8.test.cki available here
https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=27943933
Note this is a testing build for the upcoming kernel-4.18.0-193.9.el8


How reproducible:
easily

Steps to Reproduce:
1. stap -p4 -k -v  -e 'probe kernel.trace("iocost:iocost_ioc_vrate_adj") { if (pid() == 0) printf("probe hit\n"); }'
2.
3.

Actual results:
Pass 1: parsed user script and 478 library scripts using 238888virt/80668res/11980shr/68204data kb, in 180usr/20sys/197real ms.
Pass 2: analyzed script: 1 probe, 1 function, 0 embeds, 0 globals using 242436virt/85156res/12912shr/71752data kb, in 440usr/180sys/621real ms.
Pass 3: translated to C into "/tmp/stapoCIhdW/stap_45624_src.c" using 242436virt/85156res/12912shr/71752data kb, in 0usr/0sys/0real ms.
In file included from /tmp/stapoCIhdW/stap_45624_aux_0.c:8:
/tmp/stapoCIhdW/stap_45624_aux_0.c:15:8: error: expected ‘;’, ‘,’ or ‘)’ before ‘*’ token
 , u32[]* __tracepoint_arg_missed_ppm


/tmp/stapoCIhdW/stap_45624_aux_0.c

include <trace/events/iocost.h>
STP_TRACE_ENTER_REAL_NOARGS(enter_real_tracepoint_probe_0);
static STP_TRACE_ENTER(enter_tracepoint_probe_0
, struct ioc* __tracepoint_arg_ioc
, u64 __tracepoint_arg_new_vrate
, u32[]* __tracepoint_arg_missed_ppm
  ^^^^^
  vs u32 (*)[2] / u32 (*__tracepoint_arg_missed_ppm)[2]
, u32 __tracepoint_arg_rq_wait_pct
, int __tracepoint_arg_nr_lagging
, int __tracepoint_arg_nr_shortages
, int __tracepoint_arg_nr_surpluses
)
{
  enter_real_tracepoint_probe_0(
      );
}


Expected results:
module for iocost_ioc_vrate_adj can be compiled and used

Additional info: