From: Waiman Long longman@redhat.com
commit d6c8e949a35d6906d6c03a50e9a9cdf4e494528a upstream.
Systemtap 4.2 is unable to correctly interpret the "u32 (*missed_ppm)[2]" argument of the iocost_ioc_vrate_adj trace entry defined in include/trace/events/iocost.h leading to the following error:
/tmp/stapAcz0G0/stap_c89c58b83cea1724e26395efa9ed4939_6321_aux_6.c:78:8: error: expected ‘;’, ‘,’ or ‘)’ before ‘*’ token , u32[]* __tracepoint_arg_missed_ppm
That argument type is indeed rather complex and hard to read. Looking at block/blk-iocost.c. It is just a 2-entry u32 array. By simplifying the argument to a simple "u32 *missed_ppm" and adjusting the trace entry accordingly, the compilation error was gone.
Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost") Acked-by: Steven Rostedt (VMware) rostedt@goodmis.org Acked-by: Tejun Heo tj@kernel.org Signed-off-by: Waiman Long longman@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- block/blk-iocost.c | 4 ++-- include/trace/events/iocost.h | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-)
--- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1594,7 +1594,7 @@ skip_surplus_transfers: vrate_min, vrate_max); }
- trace_iocost_ioc_vrate_adj(ioc, vrate, &missed_ppm, rq_wait_pct, + trace_iocost_ioc_vrate_adj(ioc, vrate, missed_ppm, rq_wait_pct, nr_lagging, nr_shortages, nr_surpluses);
@@ -1603,7 +1603,7 @@ skip_surplus_transfers: ioc->period_us * vrate * INUSE_MARGIN_PCT, 100); } else if (ioc->busy_level != prev_busy_level || nr_lagging) { trace_iocost_ioc_vrate_adj(ioc, atomic64_read(&ioc->vtime_rate), - &missed_ppm, rq_wait_pct, nr_lagging, + missed_ppm, rq_wait_pct, nr_lagging, nr_shortages, nr_surpluses); }
--- a/include/trace/events/iocost.h +++ b/include/trace/events/iocost.h @@ -130,7 +130,7 @@ DEFINE_EVENT(iocg_inuse_update, iocost_i
TRACE_EVENT(iocost_ioc_vrate_adj,
- TP_PROTO(struct ioc *ioc, u64 new_vrate, u32 (*missed_ppm)[2], + TP_PROTO(struct ioc *ioc, u64 new_vrate, u32 *missed_ppm, u32 rq_wait_pct, int nr_lagging, int nr_shortages, int nr_surpluses),
@@ -155,8 +155,8 @@ TRACE_EVENT(iocost_ioc_vrate_adj, __entry->old_vrate = atomic64_read(&ioc->vtime_rate);; __entry->new_vrate = new_vrate; __entry->busy_level = ioc->busy_level; - __entry->read_missed_ppm = (*missed_ppm)[READ]; - __entry->write_missed_ppm = (*missed_ppm)[WRITE]; + __entry->read_missed_ppm = missed_ppm[READ]; + __entry->write_missed_ppm = missed_ppm[WRITE]; __entry->rq_wait_pct = rq_wait_pct; __entry->nr_lagging = nr_lagging; __entry->nr_shortages = nr_shortages;