linux-kernel - [PATCH 02/11] blkcg: __blkg_lookup_create() doesn't have to fail on radix tree preload failure

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Message-Id: <1335477561-11131-3-git-send-email-tj@kernel.org>
Date:	Thu, 26 Apr 2012 14:59:12 -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, fengguang.wu@...el.com,
	hughd@...gle.com, akpm@...ux-foundation.org,
	Tejun Heo <tj@...nel.org>
Subject: [PATCH 02/11] blkcg: __blkg_lookup_create() doesn't have to fail on radix tree preload failure

__blkg_lookup_create() currently fails if radix_tree_preload() fails;
however, preload failrue doesn't imply insertion failure.  Don't fail
__blkg_lookup_create() on preload failure.

While at it, drop sparse locking annotation which no longer applies.

Signed-off-by: Tejun Heo <tj@...nel.org>
---
 block/blk-cgroup.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4ab7420..197fb50 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -177,9 +177,9 @@ EXPORT_SYMBOL_GPL(blkg_lookup);
 
 static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
 					     struct request_queue *q)
-	__releases(q->queue_lock) __acquires(q->queue_lock)
 {
 	struct blkcg_gq *blkg;
+	bool preloaded;
 	int ret;
 
 	WARN_ON_ONCE(!rcu_read_lock_held());
@@ -203,9 +203,7 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
 		goto err_put;
 
 	/* insert */
-	ret = radix_tree_preload(GFP_ATOMIC);
-	if (ret)
-		goto err_free;
+	preloaded = !radix_tree_preload(GFP_ATOMIC);
 
 	spin_lock(&blkcg->lock);
 	ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
@@ -215,14 +213,13 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
 	}
 	spin_unlock(&blkcg->lock);
 
-	radix_tree_preload_end();
-
+	if (preloaded)
+		radix_tree_preload_end();
 	if (!ret)
 		return blkg;
-err_free:
-	blkg_free(blkg);
 err_put:
 	css_put(&blkcg->css);
+	blkg_free(blkg);
 	return ERR_PTR(ret);
 }
 
-- 
1.7.7.3

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