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Commit bc915e61 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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blkcg: remove unnecessary blkcg_root handling from css_alloc/free paths 



blkcg_css_alloc() bypasses policy data allocation and blkcg_css_free()
bypasses policy data and blkcg freeing for blkcg_root.  There's no
reason to to treat policy data any differently for blkcg_root.  If the
root css gets allocated after policies are registered, policy
registration path will add policy data; otherwise, the alloc path
will.  The free path isn't never invoked for root csses.

This patch removes the unnecessary special handling of blkcg_root from
css_alloc/free paths.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 994b7832

block/blk-cgroup.c

+10 −15
Original line number Diff line number Diff line
@@ -823,19 +823,16 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css) 
static void blkcg_css_free(struct cgroup_subsys_state *css)

{

	struct blkcg *blkcg = css_to_blkcg(css);

	int i;



	mutex_lock(&blkcg_pol_mutex);

	list_del(&blkcg->all_blkcgs_node);

	mutex_unlock(&blkcg_pol_mutex);



	if (blkcg != &blkcg_root) {

		int i;



	for (i = 0; i < BLKCG_MAX_POLS; i++)

		kfree(blkcg->pd[i]);

	kfree(blkcg);

}

}



static struct cgroup_subsys_state *

blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
@@ -848,14 +845,13 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 


	if (!parent_css) {

		blkcg = &blkcg_root;

		goto done;

	}



	} else {

		blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);

		if (!blkcg) {

			ret = ERR_PTR(-ENOMEM);

			goto free_blkcg;

		}

	}



	for (i = 0; i < BLKCG_MAX_POLS ; i++) {

		struct blkcg_policy *pol = blkcg_policy[i];
@@ -881,7 +877,6 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 
		pol->cpd_init_fn(blkcg);

	}



done:

	spin_lock_init(&blkcg->lock);

	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);

	INIT_HLIST_HEAD(&blkcg->blkg_list);