From 3a7faeada20d72f07d3a7b13454859025cd50a36 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 18 Aug 2015 14:55:26 -0700 Subject: [PATCH] blkcg: reduce stack usage of blkg_rwstat_recursive_sum() The recent percpu conversion of blkg_rwstat triggered the following warning in certain configurations. block/blk-cgroup.c:654:1: warning: the frame size of 1360 bytes is larger than 1024 bytes This is because blkg_rwstat now contains four percpu_counter which can be pretty big depending on debug options although it shouldn't be a problem in production configs. This patch removes one of the two local blkg_rwstat variables used by blkg_rwstat_recursive_sum() to reduce stack usage. Signed-off-by: Tejun Heo Cc: Vivek Goyal Reported-by: kbuild test robot Link: http://article.gmane.org/gmane.linux.kernel.cgroups/13835 Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index a25263ca39ca..c82c5dbf9187 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -744,7 +744,7 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, rcu_read_lock(); blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) { - struct blkg_rwstat *rwstat, tmp; + struct blkg_rwstat *rwstat; if (!pos_blkg->online) continue; @@ -754,12 +754,10 @@ struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg, else rwstat = (void *)pos_blkg + off; - tmp = blkg_rwstat_read(rwstat); - for (i = 0; i < BLKG_RWSTAT_NR; i++) - atomic64_add(atomic64_read(&tmp.aux_cnt[i]) + - atomic64_read(&rwstat->aux_cnt[i]), - &sum.aux_cnt[i]); + atomic64_add(atomic64_read(&rwstat->aux_cnt[i]) + + percpu_counter_sum_positive(&rwstat->cpu_cnt[i]), + &sum.aux_cnt[i]); } rcu_read_unlock();