diff options
| -rw-r--r-- | Documentation/cgroups/cgroups.txt | 20 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 2 | ||||
| -rw-r--r-- | kernel/cgroup.c | 4 |
3 files changed, 21 insertions, 5 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 2b51e12ce178..638bf17ff869 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -211,9 +211,10 @@ matches, and any of the requested subsystems are in use in an existing hierarchy, the mount will fail with -EBUSY. Otherwise, a new hierarchy is activated, associated with the requested subsystems. -It's not possible to bind a new subsystem to an active cgroup -hierarchy, or to unbind a subsystem from an active cgroup -hierarchy. +It's not currently possible to bind a new subsystem to an active +cgroup hierarchy, or to unbind a subsystem from an active cgroup +hierarchy. This may be possible in future, but is fraught with nasty +error-recovery issues. When a cgroup filesystem is unmounted, if there are any child cgroups created below the top-level cgroup, that hierarchy @@ -381,8 +382,10 @@ To Specify a hierarchy's release_agent: Note that specifying 'release_agent' more than once will return failure. -Note that changing the set of subsystems is only supported when the -hierarchy consists of a single (root) cgroup. +Note that changing the set of subsystems is currently only supported +when the hierarchy consists of a single (root) cgroup. Supporting +the ability to arbitrarily bind/unbind subsystems from an existing +cgroup hierarchy is intended to be implemented in the future. Then under /sys/fs/cgroup/rg1 you can find a tree that corresponds to the tree of the cgroups in the system. For instance, /sys/fs/cgroup/rg1 @@ -640,6 +643,13 @@ void exit(struct task_struct *task) Called during task exit. +void bind(struct cgroup *root) +(cgroup_mutex held by caller) + +Called when a cgroup subsystem is rebound to a different hierarchy +and root cgroup. Currently this will only involve movement between +the default hierarchy (which never has sub-cgroups) and a hierarchy +that is being created/destroyed (and hence has no sub-cgroups). 4. Extended attribute usage =========================== diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index a2b9d4b13369..45aee0fc6b98 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -484,6 +484,8 @@ struct cgroup_subsys { void (*fork)(struct task_struct *task); void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp, struct task_struct *task); + void (*bind)(struct cgroup *root); + int subsys_id; int active; int disabled; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7bf3ce09c50c..678a22c75fdb 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1091,12 +1091,16 @@ static int rebind_subsystems(struct cgroupfs_root *root, cgrp->subsys[i]->cgroup = cgrp; list_move(&ss->sibling, &root->subsys_list); ss->root = root; + if (ss->bind) + ss->bind(cgrp); /* refcount was already taken, and we're keeping it */ } else if (bit & removed_mask) { /* We're removing this subsystem */ BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); BUG_ON(cgrp->subsys[i]->cgroup != cgrp); + if (ss->bind) + ss->bind(dummytop); dummytop->subsys[i]->cgroup = dummytop; cgrp->subsys[i] = NULL; subsys[i]->root = &rootnode; |