diff options
| -rw-r--r-- | kernel/cgroup.c | 100 |
1 files changed, 56 insertions, 44 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 78017f52c69b..b632981bd9c7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -175,8 +175,8 @@ static int need_forkexit_callback __read_mostly; static struct cftype cgroup_base_files[]; static void cgroup_put(struct cgroup *cgrp); -static int rebind_subsystems(struct cgroupfs_root *root, - unsigned long added_mask, unsigned removed_mask); +static int rebind_subsystems(struct cgroupfs_root *dst_root, + unsigned long ss_mask); static void cgroup_destroy_css_killed(struct cgroup *cgrp); static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], @@ -739,7 +739,7 @@ static void cgroup_destroy_root(struct cgroupfs_root *root) BUG_ON(!list_empty(&cgrp->children)); /* Rebind all subsystems back to the default hierarchy */ - WARN_ON(rebind_subsystems(root, 0, root->subsys_mask)); + rebind_subsystems(&cgroup_dummy_root, root->subsys_mask); /* * Release all the links from cset_links to this hierarchy's @@ -976,69 +976,77 @@ static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) } } -static int rebind_subsystems(struct cgroupfs_root *root, - unsigned long added_mask, unsigned removed_mask) +static int rebind_subsystems(struct cgroupfs_root *dst_root, + unsigned long ss_mask) { - struct cgroup *cgrp = &root->top_cgroup; + struct cgroup *dst_top = &dst_root->top_cgroup; struct cgroup_subsys *ss; - int i, ret; + int ssid, ret; lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); - /* Check that any added subsystems are currently free */ - for_each_subsys(ss, i) - if ((added_mask & (1 << i)) && ss->root != &cgroup_dummy_root) + for_each_subsys(ss, ssid) { + if (!(ss_mask & (1 << ssid))) + continue; + + /* if @ss is on the dummy_root, we can always move it */ + if (ss->root == &cgroup_dummy_root) + continue; + + /* if @ss has non-root cgroups attached to it, can't move */ + if (!list_empty(&ss->root->top_cgroup.children)) return -EBUSY; - ret = cgroup_populate_dir(cgrp, added_mask); - if (ret) - return ret; + /* can't move between two non-dummy roots either */ + if (dst_root != &cgroup_dummy_root) + return -EBUSY; + } + + if (dst_root != &cgroup_dummy_root) { + ret = cgroup_populate_dir(dst_top, ss_mask); + if (ret) + return ret; + } /* * Nothing can fail from this point on. Remove files for the * removed subsystems and rebind each subsystem. */ mutex_unlock(&cgroup_mutex); - cgroup_clear_dir(cgrp, removed_mask); + for_each_subsys(ss, ssid) + if ((ss_mask & (1 << ssid)) && ss->root != &cgroup_dummy_root) + cgroup_clear_dir(&ss->root->top_cgroup, 1 << ssid); mutex_lock(&cgroup_mutex); - for_each_subsys(ss, i) { - unsigned long bit = 1UL << i; - - if (bit & added_mask) { - /* We're binding this subsystem to this hierarchy */ - BUG_ON(cgroup_css(cgrp, ss)); - BUG_ON(!cgroup_css(cgroup_dummy_top, ss)); - BUG_ON(cgroup_css(cgroup_dummy_top, ss)->cgroup != cgroup_dummy_top); + for_each_subsys(ss, ssid) { + struct cgroupfs_root *src_root; + struct cgroup *src_top; + struct cgroup_subsys_state *css; - rcu_assign_pointer(cgrp->subsys[i], - cgroup_css(cgroup_dummy_top, ss)); - cgroup_css(cgrp, ss)->cgroup = cgrp; + if (!(ss_mask & (1 << ssid))) + continue; - ss->root = root; - if (ss->bind) - ss->bind(cgroup_css(cgrp, ss)); + src_root = ss->root; + src_top = &src_root->top_cgroup; + css = cgroup_css(src_top, ss); - /* refcount was already taken, and we're keeping it */ - root->subsys_mask |= bit; - } else if (bit & removed_mask) { - /* We're removing this subsystem */ - BUG_ON(cgroup_css(cgrp, ss) != cgroup_css(cgroup_dummy_top, ss)); - BUG_ON(cgroup_css(cgrp, ss)->cgroup != cgrp); + WARN_ON(!css || cgroup_css(dst_top, ss)); - if (ss->bind) - ss->bind(cgroup_css(cgroup_dummy_top, ss)); + RCU_INIT_POINTER(src_top->subsys[ssid], NULL); + rcu_assign_pointer(dst_top->subsys[ssid], css); + ss->root = dst_root; + css->cgroup = dst_top; - cgroup_css(cgroup_dummy_top, ss)->cgroup = cgroup_dummy_top; - RCU_INIT_POINTER(cgrp->subsys[i], NULL); + src_root->subsys_mask &= ~(1 << ssid); + dst_root->subsys_mask |= 1 << ssid; - cgroup_subsys[i]->root = &cgroup_dummy_root; - root->subsys_mask &= ~bit; - } + if (ss->bind) + ss->bind(css); } - kernfs_activate(cgrp->kn); + if (dst_root != &cgroup_dummy_root) + kernfs_activate(dst_top->kn); return 0; } @@ -1277,10 +1285,12 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) goto out_unlock; } - ret = rebind_subsystems(root, added_mask, removed_mask); + ret = rebind_subsystems(root, added_mask); if (ret) goto out_unlock; + rebind_subsystems(&cgroup_dummy_root, removed_mask); + if (opts.release_agent) { spin_lock(&release_agent_path_lock); strcpy(root->release_agent_path, opts.release_agent); @@ -1420,7 +1430,7 @@ static int cgroup_setup_root(struct cgroupfs_root *root, unsigned long ss_mask) if (ret) goto destroy_root; - ret = rebind_subsystems(root, ss_mask, 0); + ret = rebind_subsystems(root, ss_mask); if (ret) goto destroy_root; @@ -4026,6 +4036,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) BUG_ON(online_css(css)); + cgroup_dummy_root.subsys_mask |= 1 << ss->id; + mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); } |