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authorTejun Heo <tj@kernel.org>2015-08-18 14:55:26 -0700
committerJens Axboe <axboe@fb.com>2015-08-18 15:49:18 -0700
commit3a7faeada20d72f07d3a7b13454859025cd50a36 (patch)
tree01dc2b90eab2db6680d1f433c130e57351ee281c /block/blk-cgroup.c
parent702747cabe737fe9b358739443d539f10cc7c715 (diff)
downloadlinux-3a7faeada20d72f07d3a7b13454859025cd50a36.tar.bz2
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 <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Reported-by: kbuild test robot <fengguang.wu@intel.com> Link: http://article.gmane.org/gmane.linux.kernel.cgroups/13835 Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-cgroup.c')
-rw-r--r--block/blk-cgroup.c10
1 files 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();