diff options
| -rw-r--r-- | Documentation/cgroups/cgroups.txt | 27 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 17 | ||||
| -rw-r--r-- | kernel/cgroup.c | 47 |
3 files changed, 10 insertions, 81 deletions
diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index 8e74980ab385..4a0b64c605fc 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -370,15 +370,12 @@ To mount a cgroup hierarchy with just the cpuset and memory subsystems, type: # mount -t cgroup -o cpuset,memory hier1 /sys/fs/cgroup/rg1 -To change the set of subsystems bound to a mounted hierarchy, just -remount with different options: -# mount -o remount,cpuset,blkio hier1 /sys/fs/cgroup/rg1 - -Now memory is removed from the hierarchy and blkio is added. - -Note this will add blkio to the hierarchy but won't remove memory or -cpuset, because the new options are appended to the old ones: -# mount -o remount,blkio /sys/fs/cgroup/rg1 +While remounting cgroups is currently supported, it is not recommend +to use it. Remounting allows changing bound subsystems and +release_agent. Rebinding is hardly useful as it only works when the +hierarchy is empty and release_agent itself should be replaced with +conventional fsnotify. The support for remounting will be removed in +the future. To Specify a hierarchy's release_agent: # mount -t cgroup -o cpuset,release_agent="/sbin/cpuset_release_agent" \ @@ -637,16 +634,6 @@ void exit(struct task_struct *task) Called during task exit. -int populate(struct cgroup *cgrp) -(cgroup_mutex held by caller) - -Called after creation of a cgroup to allow a subsystem to populate -the cgroup directory with file entries. The subsystem should make -calls to cgroup_add_file() with objects of type cftype (see -include/linux/cgroup.h for details). Note that although this -method can return an error code, the error code is currently not -always handled well. - void post_clone(struct cgroup *cgrp) (cgroup_mutex held by caller) @@ -656,7 +643,7 @@ example in cpusets, no task may attach before 'cpus' and 'mems' are set up. void bind(struct cgroup *root) -(cgroup_mutex and ss->hierarchy_mutex held by caller) +(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 diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index d3f5fba2c159..c90eaa803440 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -500,21 +500,8 @@ struct cgroup_subsys { const char *name; /* - * Protects sibling/children links of cgroups in this - * hierarchy, plus protects which hierarchy (or none) the - * subsystem is a part of (i.e. root/sibling). To avoid - * potential deadlocks, the following operations should not be - * undertaken while holding any hierarchy_mutex: - * - * - allocating memory - * - initiating hotplug events - */ - struct mutex hierarchy_mutex; - struct lock_class_key subsys_key; - - /* * Link to parent, and list entry in parent's children. - * Protected by this->hierarchy_mutex and cgroup_lock() + * Protected by cgroup_lock() */ struct cgroupfs_root *root; struct list_head sibling; @@ -602,7 +589,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); * the lifetime of cgroup_subsys_state is subsys's matter. * * Looking up and scanning function should be called under rcu_read_lock(). - * Taking cgroup_mutex()/hierarchy_mutex() is not necessary for following calls. + * Taking cgroup_mutex is not necessary for following calls. * But the css returned by this routine can be "not populated yet" or "being * destroyed". The caller should check css and cgroup's status. */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index af2b5641fc8b..79818507e444 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -954,7 +954,7 @@ static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) dget(d); d_delete(d); - simple_unlink(d->d_inode, d); + simple_unlink(cgrp->dentry->d_inode, d); list_del_init(&cfe->node); dput(d); @@ -1068,28 +1068,24 @@ static int rebind_subsystems(struct cgroupfs_root *root, BUG_ON(cgrp->subsys[i]); BUG_ON(!dummytop->subsys[i]); BUG_ON(dummytop->subsys[i]->cgroup != dummytop); - mutex_lock(&ss->hierarchy_mutex); cgrp->subsys[i] = dummytop->subsys[i]; cgrp->subsys[i]->cgroup = cgrp; list_move(&ss->sibling, &root->subsys_list); ss->root = root; if (ss->bind) ss->bind(cgrp); - mutex_unlock(&ss->hierarchy_mutex); /* refcount was already taken, and we're keeping it */ } else if (bit & removed_bits) { /* We're removing this subsystem */ BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); BUG_ON(cgrp->subsys[i]->cgroup != cgrp); - mutex_lock(&ss->hierarchy_mutex); if (ss->bind) ss->bind(dummytop); dummytop->subsys[i]->cgroup = dummytop; cgrp->subsys[i] = NULL; subsys[i]->root = &rootnode; list_move(&ss->sibling, &rootnode.subsys_list); - mutex_unlock(&ss->hierarchy_mutex); /* subsystem is now free - drop reference on module */ module_put(ss->module); } else if (bit & final_bits) { @@ -3915,37 +3911,6 @@ static void init_cgroup_css(struct cgroup_subsys_state *css, set_bit(CSS_CLEAR_CSS_REFS, &css->flags); } -static void cgroup_lock_hierarchy(struct cgroupfs_root *root) -{ - /* We need to take each hierarchy_mutex in a consistent order */ - int i; - - /* - * No worry about a race with rebind_subsystems that might mess up the - * locking order, since both parties are under cgroup_mutex. - */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss == NULL) - continue; - if (ss->root == root) - mutex_lock(&ss->hierarchy_mutex); - } -} - -static void cgroup_unlock_hierarchy(struct cgroupfs_root *root) -{ - int i; - - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = subsys[i]; - if (ss == NULL) - continue; - if (ss->root == root) - mutex_unlock(&ss->hierarchy_mutex); - } -} - /* * cgroup_create - create a cgroup * @parent: cgroup that will be parent of the new cgroup @@ -4006,9 +3971,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, ss->post_clone(cgrp); } - cgroup_lock_hierarchy(root); list_add(&cgrp->sibling, &cgrp->parent->children); - cgroup_unlock_hierarchy(root); root->number_of_cgroups++; err = cgroup_create_dir(cgrp, dentry, mode); @@ -4035,9 +3998,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, err_remove: - cgroup_lock_hierarchy(root); list_del(&cgrp->sibling); - cgroup_unlock_hierarchy(root); root->number_of_cgroups--; err_destroy: @@ -4245,10 +4206,8 @@ again: list_del_init(&cgrp->release_list); raw_spin_unlock(&release_list_lock); - cgroup_lock_hierarchy(cgrp->root); /* delete this cgroup from parent->children */ list_del_init(&cgrp->sibling); - cgroup_unlock_hierarchy(cgrp->root); list_del_init(&cgrp->allcg_node); @@ -4322,8 +4281,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) * need to invoke fork callbacks here. */ BUG_ON(!list_empty(&init_task.tasks)); - mutex_init(&ss->hierarchy_mutex); - lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); ss->active = 1; /* this function shouldn't be used with modular subsystems, since they @@ -4450,8 +4407,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) } write_unlock(&css_set_lock); - mutex_init(&ss->hierarchy_mutex); - lockdep_set_class(&ss->hierarchy_mutex, &ss->subsys_key); ss->active = 1; /* success! */ |