blkcg: remove unnecessary blkcg_root handling from css_alloc/free paths (bc915e61) · Commits · 戴 / test

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:

Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

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);

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