Commit d6c8e949 authored by Waiman Long's avatar Waiman Long Committed by Jens Axboe
Browse files

blk-iocost: Fix error on iocost_ioc_vrate_adj 



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: 7caa4715 ("blkcg: implement blk-iocost")
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b849dd84

block/blk-iocost.c

+2 −2
Original line number Diff line number Diff line
@@ -1591,7 +1591,7 @@ 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);
@@ -1600,7 +1600,7 @@ 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);

	}

include/trace/events/iocost.h

+3 −3
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ DEFINE_EVENT(iocg_inuse_update, iocost_inuse_reset, 


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;

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