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From: Tejun Heo <tj@kernel.org>
To: axboe@kernel.dk, jbacik@fb.com
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	kernel-team@fb.com, dennis@kernel.org, jack@suse.cz,
	Tejun Heo <tj@kernel.org>
Subject: [PATCH 4/5] blkcg: blkcg_activate_policy() should initialize ancestors first
Date: Thu, 13 Jun 2019 15:30:40 -0700	[thread overview]
Message-ID: <20190613223041.606735-5-tj@kernel.org> (raw)
In-Reply-To: <20190613223041.606735-1-tj@kernel.org>

When blkcg_activate_policy() is creating blkg_policy_data for existing
blkgs, it did in the wrong order - descendants first.  Fix it.  None
of the existing controllers seem affected by this.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 block/blk-cgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 04d286934c5e..440797293235 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1390,7 +1390,8 @@ int blkcg_activate_policy(struct request_queue *q,
 
 	spin_lock_irq(&q->queue_lock);
 
-	list_for_each_entry(blkg, &q->blkg_list, q_node) {
+	/* blkg_list is pushed at the head, reverse walk to init parents first */
+	list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) {
 		struct blkg_policy_data *pd;
 
 		if (blkg->pd[pol->plid])
-- 
2.17.1


  parent reply	other threads:[~2019-06-13 22:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13 22:30 [PATCHSET block/for-linus] Assorted blkcg fixes Tejun Heo
2019-06-13 22:30 ` [PATCH 1/5] blk-iolatency: clear use_delay when io.latency is set to zero Tejun Heo
2019-06-13 22:30 ` [PATCH 2/5] blkcg: update blkcg_print_stat() to handle larger outputs Tejun Heo
2019-06-13 22:30 ` [PATCH 3/5] blkcg: perpcu_ref init/exit should be done from blkg_alloc/free() Tejun Heo
2019-06-13 22:30 ` Tejun Heo [this message]
2019-06-13 22:30 ` [PATCH 5/5] blkcg, writeback: dead memcgs shouldn't contribute to writeback ownership arbitration Tejun Heo
2019-06-19 11:20   ` Jan Kara
2019-06-15  7:40 ` [PATCHSET block/for-linus] Assorted blkcg fixes Jens Axboe
2019-06-15 15:50   ` Tejun Heo
2019-06-15 16:40     ` Jens Axboe

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