This is a note to let you know that I've just added the patch titled blk-iocost: Fix error on iocost_ioc_vrate_adj to the 5.6-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: blk-iocost-fix-error-on-iocost_ioc_vrate_adj.patch and it can be found in the queue-5.6 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d6c8e949a35d6906d6c03a50e9a9cdf4e494528a Mon Sep 17 00:00:00 2001 From: Waiman Long <longman@xxxxxxxxxx> Date: Tue, 21 Apr 2020 09:07:55 -0400 Subject: blk-iocost: Fix error on iocost_ioc_vrate_adj MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Waiman Long <longman@xxxxxxxxxx> 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@xxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Waiman Long <longman@xxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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; Patches currently in stable-queue which might be from longman@xxxxxxxxxx are queue-5.6/blk-iocost-fix-error-on-iocost_ioc_vrate_adj.patch