linux-kernel - [PATCH 11/11] blkcg: shoot down blkgs if all policies are deactivated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1334347895-6268-12-git-send-email-tj@kernel.org>
Date:	Fri, 13 Apr 2012 13:11:35 -0700
From:	Tejun Heo <tj@...nel.org>
To:	axboe@...nel.dk
Cc:	vgoyal@...hat.com, ctalbott@...gle.com, rni@...gle.com,
	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	containers@...ts.linux-foundation.org, Tejun Heo <tj@...nel.org>
Subject: [PATCH 11/11] blkcg: shoot down blkgs if all policies are deactivated

There's no reason to keep blkgs around if no policy is activated for
the queue.  This patch moves queue locking out of blkg_destroy_all()
and call it from blkg_deactivate_policy() on deactivation of the last
policy on the queue.

This change was suggested by Vivek.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Vivek Goyal <vgoyal@...hat.com>
---
 block/blk-cgroup.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 10f0d2f..b1807d4 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -258,7 +258,7 @@ static void blkg_destroy_all(struct request_queue *q)
 {
 	struct blkio_group *blkg, *n;
 
-	spin_lock_irq(q->queue_lock);
+	lockdep_assert_held(q->queue_lock);
 
 	list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) {
 		struct blkio_cgroup *blkcg = blkg->blkcg;
@@ -267,8 +267,6 @@ static void blkg_destroy_all(struct request_queue *q)
 		blkg_destroy(blkg);
 		spin_unlock(&blkcg->lock);
 	}
-
-	spin_unlock_irq(q->queue_lock);
 }
 
 static void blkg_rcu_free(struct rcu_head *rcu_head)
@@ -646,7 +644,10 @@ void blkcg_drain_queue(struct request_queue *q)
  */
 void blkcg_exit_queue(struct request_queue *q)
 {
+	spin_lock_irq(q->queue_lock);
 	blkg_destroy_all(q);
+	spin_unlock_irq(q->queue_lock);
+
 	blk_throtl_exit(q);
 }
 
@@ -802,6 +803,10 @@ void blkcg_deactivate_policy(struct request_queue *q,
 
 	__clear_bit(pol->plid, q->blkcg_pols);
 
+	/* if no policy is left, no need for blkgs - shoot them down */
+	if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS))
+		blkg_destroy_all(q);
+
 	list_for_each_entry(blkg, &q->blkg_list, q_node) {
 		/* grab blkcg lock too while removing @pd from @blkg */
 		spin_lock(&blkg->blkcg->lock);
-- 
1.7.7.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/