From e595cd706982bff0211e6fafe5a108421e747fbc Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 15 Jan 2017 19:03:41 -0500 Subject: cgroup: track migration context in cgroup_mgctx cgroup migration is performed in four steps - css_set preloading, addition of target tasks, actual migration, and clean up. A list named preloaded_csets is used to track the preloading. This is a bit too restricted and the code is already depending on the subtlety that all source css_sets appear before destination ones. Let's create struct cgroup_mgctx which keeps track of everything during migration. Currently, it has separate preload lists for source and destination csets and also embeds cgroup_taskset which is used during the actual migration. This moves struct cgroup_taskset definition to cgroup-internal.h. This patch doesn't cause any functional changes. Signed-off-by: Tejun Heo Acked-by: Zefan Li --- kernel/cgroup/cgroup-internal.h | 66 +++++++++++++++++++++++++++++++++++++---- 1 file changed, 60 insertions(+), 6 deletions(-) (limited to 'kernel/cgroup/cgroup-internal.h') diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 589b0e7013ec..5f8c8ac5ab88 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -26,6 +26,61 @@ struct cgrp_cset_link { struct list_head cgrp_link; }; +/* used to track tasks and csets during migration */ +struct cgroup_taskset { + /* the src and dst cset list running through cset->mg_node */ + struct list_head src_csets; + struct list_head dst_csets; + + /* the subsys currently being processed */ + int ssid; + + /* + * Fields for cgroup_taskset_*() iteration. + * + * Before migration is committed, the target migration tasks are on + * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of + * the csets on ->dst_csets. ->csets point to either ->src_csets + * or ->dst_csets depending on whether migration is committed. + * + * ->cur_csets and ->cur_task point to the current task position + * during iteration. + */ + struct list_head *csets; + struct css_set *cur_cset; + struct task_struct *cur_task; +}; + +/* migration context also tracks preloading */ +struct cgroup_mgctx { + /* + * Preloaded source and destination csets. Used to guarantee + * atomic success or failure on actual migration. + */ + struct list_head preloaded_src_csets; + struct list_head preloaded_dst_csets; + + /* tasks and csets to migrate */ + struct cgroup_taskset tset; +}; + +#define CGROUP_TASKSET_INIT(tset) \ +{ \ + .src_csets = LIST_HEAD_INIT(tset.src_csets), \ + .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ + .csets = &tset.src_csets, \ +} + +#define CGROUP_MGCTX_INIT(name) \ +{ \ + LIST_HEAD_INIT(name.preloaded_src_csets), \ + LIST_HEAD_INIT(name.preloaded_dst_csets), \ + CGROUP_TASKSET_INIT(name.tset), \ +} + +#define DEFINE_CGROUP_MGCTX(name) \ + struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name) + struct cgroup_sb_opts { u16 subsys_mask; unsigned int flags; @@ -112,13 +167,12 @@ struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags, struct cgroup_namespace *ns); bool cgroup_may_migrate_to(struct cgroup *dst_cgrp); -void cgroup_migrate_finish(struct list_head *preloaded_csets); -void cgroup_migrate_add_src(struct css_set *src_cset, - struct cgroup *dst_cgrp, - struct list_head *preloaded_csets); -int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets); +void cgroup_migrate_finish(struct cgroup_mgctx *mgctx); +void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp, + struct cgroup_mgctx *mgctx); +int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx); int cgroup_migrate(struct task_struct *leader, bool threadgroup, - struct cgroup_root *root); + struct cgroup_mgctx *mgctx, struct cgroup_root *root); int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, bool threadgroup); -- cgit v1.2.3