linux-kernel - [PATCH UPDATED 02/11] blkcg: __blkg_lookup

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Message-ID: <20120427211827.GQ26595@google.com>
Date:	Fri, 27 Apr 2012 14:18:27 -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
Subject: [PATCH UPDATED 02/11] blkcg: __blkg_lookup_create() doesn't need
 radix preload

There's no point in calling radix_tree_preload() if preloading doesn't
use more permissible GFP mask.  Drop preloading from
__blkg_lookup_create().

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

v2: Vivek pointed out the odd preload usage.  Instead of updating,
    just drop it.

Signed-off-by: Tejun Heo <tj@...nel.org>
Cc: Vivek Goyal <vgoyal@...hat.com>
---
We don't need preloading at all.  Just drop it.  git branch updated
accordingly.  All patches apply as-is.

Thanks.

 block/blk-cgroup.c |   10 +---------
 1 files changed, 1 insertions(+), 9 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4ab7420..af61db0 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -177,7 +177,6 @@ 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;
 	int ret;
@@ -203,10 +202,6 @@ 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;
-
 	spin_lock(&blkcg->lock);
 	ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg);
 	if (likely(!ret)) {
@@ -215,14 +210,11 @@ static struct blkcg_gq *__blkg_lookup_create(struct blkcg *blkcg,
 	}
 	spin_unlock(&blkcg->lock);
 
-	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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