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authorTejun Heo <tj@kernel.org>2013-06-24 15:21:48 -0700
committerTejun Heo <tj@kernel.org>2013-06-24 15:21:48 -0700
commitb326f9d0dbd066b0aafbe88e6011a680a36de6e8 (patch)
tree4e2234cea36ac5ff5e7c8243100e421c2d9e4a8c /kernel
parenta8a648c4acee2095262f7fa65b0d8a68a03c32e4 (diff)
downloadop-kernel-dev-b326f9d0dbd066b0aafbe88e6011a680a36de6e8.zip
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cgroup: clean up find_css_set() and friends
find_css_set() passes uninitialized on-stack template[] array to find_existing_css_set() which sets the entries for all subsystems. Passing around an uninitialized array is a bit icky and we want to introduce an iterator which only iterates loaded subsystems. Let's initialize it on definition. While at it, also make the following cosmetic cleanups. * Convert to proper /** comments. * Reorder variable declarations. * Replace comment on synchronization with lockdep_assert_held(). This patch doesn't make any functional differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c38
1 files changed, 17 insertions, 21 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 67fc953..c8d3175 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -434,7 +434,7 @@ static inline void put_css_set_taskexit(struct css_set *cset)
__put_css_set(cset, 1);
}
-/*
+/**
* compare_css_sets - helper function for find_existing_css_set().
* @cset: candidate css_set being tested
* @old_cset: existing css_set for a task
@@ -506,27 +506,20 @@ static bool compare_css_sets(struct css_set *cset,
return true;
}
-/*
- * find_existing_css_set() is a helper for
- * find_css_set(), and checks to see whether an existing
- * css_set is suitable.
- *
- * oldcg: the cgroup group that we're using before the cgroup
- * transition
- *
- * cgrp: the cgroup that we're moving into
- *
- * template: location in which to build the desired set of subsystem
- * state objects for the new cgroup group
+/**
+ * find_existing_css_set - init css array and find the matching css_set
+ * @old_cset: the css_set that we're using before the cgroup transition
+ * @cgrp: the cgroup that we're moving into
+ * @template: out param for the new set of csses, should be clear on entry
*/
static struct css_set *find_existing_css_set(struct css_set *old_cset,
struct cgroup *cgrp,
struct cgroup_subsys_state *template[])
{
- int i;
struct cgroupfs_root *root = cgrp->root;
struct css_set *cset;
unsigned long key;
+ int i;
/*
* Build the set of subsystem state objects that we want to see in the
@@ -618,22 +611,25 @@ static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
list_add_tail(&link->cgrp_link, &cset->cgrp_links);
}
-/*
- * find_css_set() takes an existing cgroup group and a
- * cgroup object, and returns a css_set object that's
- * equivalent to the old group, but with the given cgroup
- * substituted into the appropriate hierarchy. Must be called with
- * cgroup_mutex held
+/**
+ * find_css_set - return a new css_set with one cgroup updated
+ * @old_cset: the baseline css_set
+ * @cgrp: the cgroup to be updated
+ *
+ * Return a new css_set that's equivalent to @old_cset, but with @cgrp
+ * substituted into the appropriate hierarchy.
*/
static struct css_set *find_css_set(struct css_set *old_cset,
struct cgroup *cgrp)
{
+ struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
struct css_set *cset;
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT];
struct list_head tmp_links;
struct cgrp_cset_link *link;
unsigned long key;
+ lockdep_assert_held(&cgroup_mutex);
+
/* First see if we already have a cgroup group that matches
* the desired set */
read_lock(&css_set_lock);
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