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authorTejun Heo <tj@kernel.org>2016-03-08 11:51:26 -0500
committerTejun Heo <tj@kernel.org>2016-03-08 11:51:26 -0500
commite4857982f49d21c05a84351b56724bf353022355 (patch)
treedc2e6039b714635e36ab148ed1ef20a9cbb01f4a /include/linux/cgroup-defs.h
parent37ff9f8f474216d0cfca7565a4e0caa521ee6e7e (diff)
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cgroup: use css_set->mg_dst_cgrp for the migration target cgroup
Migration can be multi-target on the default hierarchy when a controller is enabled - processes belonging to each child cgroup have to be moved to the child cgroup itself to refresh css association. This isn't a problem for cgroup_migrate_add_src() as each source css_set still maps to single source and target cgroups; however, cgroup_migrate_prepare_dst() is called once after all source css_sets are added and thus might not have a single destination cgroup. This is currently worked around by specifying NULL for @dst_cgrp and using the source's default cgroup as destination as the only multi-target migration in use is self-targetting. While this works, it's subtle and clunky. As all taget cgroups are already specified while preparing the source css_sets, this clunkiness can easily be removed by recording the target cgroup in each source css_set. This patch adds css_set->mg_dst_cgrp which is recorded on cgroup_migrate_src() and used by cgroup_migrate_prepare_dst(). This also makes migration code ready for arbitrary multi-target migration. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/cgroup-defs.h')
-rw-r--r--include/linux/cgroup-defs.h9
1 files changed, 5 insertions, 4 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index aae8c94de4b3..590291d56049 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -191,12 +191,13 @@ struct css_set {
/*
* If this cset is acting as the source of migration the following
- * two fields are set. mg_src_cgrp is the source cgroup of the
- * on-going migration and mg_dst_cset is the destination cset the
- * target tasks on this cset should be migrated to. Protected by
- * cgroup_mutex.
+ * two fields are set. mg_src_cgrp and mg_dst_cgrp are
+ * respectively the source and destination cgroups of the on-going
+ * migration. mg_dst_cset is the destination cset the target tasks
+ * on this cset should be migrated to. Protected by cgroup_mutex.
*/
struct cgroup *mg_src_cgrp;
+ struct cgroup *mg_dst_cgrp;
struct css_set *mg_dst_cset;
/*