This allows us to unbind a cgroup subsystem from a hierarchy which has sub-cgroups in it.
Due to some complexity, for now subsytems that use css_get/put() can't be unbound from such a hierarchy. Usage: # mount -t cgroup -o cpuset,cpuacct xxx /mnt # mkdir /mnt/tmp # echo $$ > /mnt/tmp/tasks (remove it from the hierarchy) # mount -o remount,cpuset xxx /mnt Signed-off-by: Li Zefan <[email protected]> --- kernel/cgroup.c | 76 ++++++++++++++++++++++++++++++++++++++++++++----------- 1 files changed, 61 insertions(+), 15 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 46df5f8..9ce3fdb 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1036,19 +1036,42 @@ static int hierarchy_attach_css(struct cgroup *cgrp, void *data) return ret; } -static int hierarchy_update_css_sets(struct cgroup *cgrp, void *data) +static int hierarchy_remove_css(struct cgroup *cgrp, void *data) { - unsigned long added_bits = (unsigned long)data; + unsigned long removed_bits = (unsigned long)data; int i; + + /* + * There might be some pointers to the cgroup_subsys_state + * that we are going to destroy. + */ + synchronize_rcu(); + + for_each_set_bit(i, &removed_bits, CGROUP_SUBSYS_COUNT) { + subsys[i]->destroy(subsys[i], cgrp); + cgrp->subsys[i] = NULL; + } + + return 0; +} + +static void hierarchy_update_css_sets(struct cgroup *cgrp, + unsigned long bits, bool add) +{ struct cg_cgroup_link *link; + int i; write_lock(&css_set_lock); list_for_each_entry(link, &cgrp->css_sets, cgrp_link_list) { struct css_set *cg = link->cg; struct hlist_head *hhead; - for_each_set_bit(i, &added_bits, CGROUP_SUBSYS_COUNT) - cg->subsys[i] = cgrp->subsys[i]; + for_each_set_bit(i, &bits, CGROUP_SUBSYS_COUNT) { + if (add) + cg->subsys[i] = cgrp->subsys[i]; + else + cg->subsys[i] = dummytop->subsys[i]; + } /* rehash */ hlist_del(&cg->hlist); @@ -1056,7 +1079,21 @@ static int hierarchy_update_css_sets(struct cgroup *cgrp, void *data) hlist_add_head(&cg->hlist, hhead); } write_unlock(&css_set_lock); +} +static int hierarchy_add_to_css_sets(struct cgroup *cgrp, void *data) +{ + unsigned long added_bits = (unsigned long)data; + + hierarchy_update_css_sets(cgrp, added_bits, true); + return 0; +} + +static int hierarchy_remove_from_css_sets(struct cgroup *cgrp, void *data) +{ + unsigned long removed_bits = (unsigned long)data; + + hierarchy_update_css_sets(cgrp, removed_bits, false); return 0; } @@ -1076,7 +1113,7 @@ static int hierarchy_populate_dir(struct cgroup *cgrp, void *data) static int rebind_subsystems(struct cgroupfs_root *root, unsigned long final_bits) { - unsigned long added_bits, removed_bits; + unsigned long added_bits, removed_bits, changed_bits; struct cgroup *cgrp = &root->top_cgroup; int i; int err; @@ -1085,6 +1122,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, removed_bits = root->actual_subsys_bits & ~final_bits; added_bits = final_bits & ~root->actual_subsys_bits; + changed_bits = removed_bits | added_bits; /* Check that any added subsystems are currently free */ for_each_set_bit(i, &added_bits, CGROUP_SUBSYS_COUNT) { @@ -1100,14 +1138,11 @@ static int rebind_subsystems(struct cgroupfs_root *root, } } - /* removing will be supported later */ - if (root->number_of_cgroups > 1 && removed_bits) - return -EBUSY; - if (root->number_of_cgroups > 1) { - for_each_set_bit(i, &added_bits, CGROUP_SUBSYS_COUNT) + for_each_set_bit(i, &changed_bits, CGROUP_SUBSYS_COUNT) if (!subsys[i]->can_bind) return -EBUSY; + } for_each_set_bit(i, &added_bits, CGROUP_SUBSYS_COUNT) { BUG_ON(cgrp->subsys[i]); @@ -1123,7 +1158,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, if (err) goto failed; - cgroup_walk_hierarchy(hierarchy_update_css_sets, + cgroup_walk_hierarchy(hierarchy_add_to_css_sets, (void *)added_bits, cgrp); /* Process each subsystem */ @@ -1143,11 +1178,7 @@ static int rebind_subsystems(struct cgroupfs_root *root, } 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); - dummytop->subsys[i]->cgroup = dummytop; - cgrp->subsys[i] = NULL; if (ss->bind) ss->bind(ss, dummytop); subsys[i]->root = &rootnode; @@ -1173,6 +1204,21 @@ static int rebind_subsystems(struct cgroupfs_root *root, } } root->subsys_bits = root->actual_subsys_bits = final_bits; + + for_each_set_bit(i, &removed_bits, CGROUP_SUBSYS_COUNT) { + BUG_ON(cgrp->subsys[i] != dummytop->subsys[i]); + BUG_ON(cgrp->subsys[i]->cgroup != cgrp); + + dummytop->subsys[i]->cgroup = dummytop; + cgrp->subsys[i] = NULL; + } + + cgroup_walk_hierarchy(hierarchy_remove_from_css_sets, + (void *)removed_bits, cgrp); + + cgroup_walk_hierarchy(hierarchy_remove_css, + (void *)removed_bits, cgrp); + synchronize_rcu(); return 0; -- 1.7.0.1 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
