diff options
| -rw-r--r-- | kernel/cgroup.c | 158 |
1 files changed, 99 insertions, 59 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 8ba6809..14efffe 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -49,6 +49,7 @@ #include <linux/namei.h> #include <linux/smp_lock.h> #include <linux/pid_namespace.h> +#include <linux/idr.h> #include <asm/atomic.h> @@ -77,6 +78,9 @@ struct cgroupfs_root { */ unsigned long subsys_bits; + /* Unique id for this hierarchy. */ + int hierarchy_id; + /* The bitmask of subsystems currently attached to this hierarchy */ unsigned long actual_subsys_bits; @@ -147,6 +151,10 @@ struct css_id { static LIST_HEAD(roots); static int root_count; +static DEFINE_IDA(hierarchy_ida); +static int next_hierarchy_id; +static DEFINE_SPINLOCK(hierarchy_id_lock); + /* dummytop is a shorthand for the dummy hierarchy's top cgroup */ #define dummytop (&rootnode.top_cgroup) @@ -264,42 +272,10 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) * compiled into their kernel but not actually in use */ static int use_task_css_set_links __read_mostly; -/* When we create or destroy a css_set, the operation simply - * takes/releases a reference count on all the cgroups referenced - * by subsystems in this css_set. This can end up multiple-counting - * some cgroups, but that's OK - the ref-count is just a - * busy/not-busy indicator; ensuring that we only count each cgroup - * once would require taking a global lock to ensure that no - * subsystems moved between hierarchies while we were doing so. - * - * Possible TODO: decide at boot time based on the number of - * registered subsystems and the number of CPUs or NUMA nodes whether - * it's better for performance to ref-count every subsystem, or to - * take a global lock and only add one ref count to each hierarchy. - */ - -/* - * unlink a css_set from the list and free it - */ -static void unlink_css_set(struct css_set *cg) +static void __put_css_set(struct css_set *cg, int taskexit) { struct cg_cgroup_link *link; struct cg_cgroup_link *saved_link; - - hlist_del(&cg->hlist); - css_set_count--; - - list_for_each_entry_safe(link, saved_link, &cg->cg_links, - cg_link_list) { - list_del(&link->cg_link_list); - list_del(&link->cgrp_link_list); - kfree(link); - } -} - -static void __put_css_set(struct css_set *cg, int taskexit) -{ - int i; /* * Ensure that the refcount doesn't hit zero while any readers * can see it. Similar to atomic_dec_and_lock(), but for an @@ -312,20 +288,27 @@ static void __put_css_set(struct css_set *cg, int taskexit) write_unlock(&css_set_lock); return; } - unlink_css_set(cg); - write_unlock(&css_set_lock); - rcu_read_lock(); - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup *cgrp = rcu_dereference(cg->subsys[i]->cgroup); + /* This css_set is dead. unlink it and release cgroup refcounts */ + hlist_del(&cg->hlist); + css_set_count--; + + list_for_each_entry_safe(link, saved_link, &cg->cg_links, + cg_link_list) { + struct cgroup *cgrp = link->cgrp; + list_del(&link->cg_link_list); + list_del(&link->cgrp_link_list); if (atomic_dec_and_test(&cgrp->count) && notify_on_release(cgrp)) { if (taskexit) set_bit(CGRP_RELEASABLE, &cgrp->flags); check_for_release(cgrp); } + + kfree(link); } - rcu_read_unlock(); + + write_unlock(&css_set_lock); kfree(cg); } @@ -519,6 +502,7 @@ static void link_css_set(struct list_head *tmp_cg_links, cgrp_link_list); link->cg = cg; link->cgrp = cgrp; + atomic_inc(&cgrp->count); list_move(&link->cgrp_link_list, &cgrp->css_sets); /* * Always add links to the tail of the list so that the list @@ -539,7 +523,6 @@ static struct css_set *find_css_set( { struct css_set *res; struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT]; - int i; struct list_head tmp_cg_links; @@ -578,10 +561,6 @@ static struct css_set *find_css_set( write_lock(&css_set_lock); /* Add reference counts and links from the new css_set. */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup *cgrp = res->subsys[i]->cgroup; - atomic_inc(&cgrp->count); - } list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { struct cgroup *c = link->cgrp; if (c->root == cgrp->root) @@ -972,8 +951,11 @@ struct cgroup_sb_opts { unsigned long flags; char *release_agent; char *name; + /* User explicitly requested empty subsystem */ + bool none; struct cgroupfs_root *new_root; + }; /* Convert a hierarchy specifier into a bitmask of subsystems and @@ -1002,6 +984,9 @@ static int parse_cgroupfs_options(char *data, if (!ss->disabled) opts->subsys_bits |= 1ul << i; } + } else if (!strcmp(token, "none")) { + /* Explicitly have no subsystems */ + opts->none = true; } else if (!strcmp(token, "noprefix")) { set_bit(ROOT_NOPREFIX, &opts->flags); } else if (!strncmp(token, "release_agent=", 14)) { @@ -1051,6 +1036,8 @@ static int parse_cgroupfs_options(char *data, } } + /* Consistency checks */ + /* * Option noprefix was introduced just for backward compatibility * with the old cpuset, so we allow noprefix only if mounting just @@ -1060,7 +1047,15 @@ static int parse_cgroupfs_options(char *data, (opts->subsys_bits & mask)) return -EINVAL; - /* We can't have an empty hierarchy */ + + /* Can't specify "none" and some subsystems */ + if (opts->subsys_bits && opts->none) + return -EINVAL; + + /* + * We either have to specify by name or by subsystems. (So all + * empty hierarchies must have a name). + */ if (!opts->subsys_bits && !opts->name) return -EINVAL; @@ -1141,6 +1136,31 @@ static void init_cgroup_root(struct cgroupfs_root *root) init_cgroup_housekeeping(cgrp); } +static bool init_root_id(struct cgroupfs_root *root) +{ + int ret = 0; + + do { + if (!ida_pre_get(&hierarchy_ida, GFP_KERNEL)) + return false; + spin_lock(&hierarchy_id_lock); + /* Try to allocate the next unused ID */ + ret = ida_get_new_above(&hierarchy_ida, next_hierarchy_id, + &root->hierarchy_id); + if (ret == -ENOSPC) + /* Try again starting from 0 */ + ret = ida_get_new(&hierarchy_ida, &root->hierarchy_id); + if (!ret) { + next_hierarchy_id = root->hierarchy_id + 1; + } else if (ret != -EAGAIN) { + /* Can only get here if the 31-bit IDR is full ... */ + BUG_ON(ret); + } + spin_unlock(&hierarchy_id_lock); + } while (ret); + return true; +} + static int cgroup_test_super(struct super_block *sb, void *data) { struct cgroup_sb_opts *opts = data; @@ -1150,8 +1170,12 @@ static int cgroup_test_super(struct super_block *sb, void *data) if (opts->name && strcmp(opts->name, root->name)) return 0; - /* If we asked for subsystems then they must match */ - if (opts->subsys_bits && (opts->subsys_bits != root->subsys_bits)) + /* + * If we asked for subsystems (or explicitly for no + * subsystems) then they must match + */ + if ((opts->subsys_bits || opts->none) + && (opts->subsys_bits != root->subsys_bits)) return 0; return 1; @@ -1161,15 +1185,19 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) { struct cgroupfs_root *root; - /* Empty hierarchies aren't supported */ - if (!opts->subsys_bits) + if (!opts->subsys_bits && !opts->none) return NULL; root = kzalloc(sizeof(*root), GFP_KERNEL); if (!root) return ERR_PTR(-ENOMEM); + if (!init_root_id(root)) { + kfree(root); + return ERR_PTR(-ENOMEM); + } init_cgroup_root(root); + root->subsys_bits = opts->subsys_bits; root->flags = opts->flags; if (opts->release_agent) @@ -1179,6 +1207,18 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) return root; } +static void cgroup_drop_root(struct cgroupfs_root *root) +{ + if (!root) + return; + + BUG_ON(!root->hierarchy_id); + spin_lock(&hierarchy_id_lock); + ida_remove(&hierarchy_ida, root->hierarchy_id); + spin_unlock(&hierarchy_id_lock); + kfree(root); +} + static int cgroup_set_super(struct super_block *sb, void *data) { int ret; @@ -1188,7 +1228,7 @@ static int cgroup_set_super(struct super_block *sb, void *data) if (!opts->new_root) return -EINVAL; - BUG_ON(!opts->subsys_bits); + BUG_ON(!opts->subsys_bits && !opts->none); ret = set_anon_super(sb, NULL); if (ret) @@ -1257,7 +1297,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type, sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); if (IS_ERR(sb)) { ret = PTR_ERR(sb); - kfree(opts.new_root); + cgroup_drop_root(opts.new_root); goto out_err; } @@ -1351,7 +1391,7 @@ static int cgroup_get_sb(struct file_system_type *fs_type, * We re-used an existing hierarchy - the new root (if * any) is not needed */ - kfree(opts.new_root); + cgroup_drop_root(opts.new_root); } simple_set_mnt(mnt, sb); @@ -1410,7 +1450,7 @@ static void cgroup_kill_sb(struct super_block *sb) { mutex_unlock(&cgroup_mutex); kill_litter_super(sb); - kfree(root); + cgroup_drop_root(root); } static struct file_system_type cgroup_fs_type = { @@ -3109,7 +3149,7 @@ int __init cgroup_init(void) /* Add init_css_set to the hash table */ hhead = css_set_hash(init_css_set.subsys); hlist_add_head(&init_css_set.hlist, hhead); - + BUG_ON(!init_root_id(&rootnode)); err = register_filesystem(&cgroup_fs_type); if (err < 0) goto out; @@ -3164,7 +3204,7 @@ static int proc_cgroup_show(struct seq_file *m, void *v) struct cgroup *cgrp; int count = 0; - seq_printf(m, "%lu:", root->subsys_bits); + seq_printf(m, "%d:", root->hierarchy_id); for_each_subsys(root, ss) seq_printf(m, "%s%s", count++ ? "," : "", ss->name); if (strlen(root->name)) @@ -3210,8 +3250,8 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v) mutex_lock(&cgroup_mutex); for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { struct cgroup_subsys *ss = subsys[i]; - seq_printf(m, "%s\t%lu\t%d\t%d\n", - ss->name, ss->root->subsys_bits, + seq_printf(m, "%s\t%d\t%d\t%d\n", + ss->name, ss->root->hierarchy_id, ss->root->number_of_cgroups, !ss->disabled); } mutex_unlock(&cgroup_mutex); @@ -3929,8 +3969,8 @@ static int current_css_set_cg_links_read(struct cgroup *cont, name = c->dentry->d_name.name; else name = "?"; - seq_printf(seq, "Root %lu group %s\n", - c->root->subsys_bits, name); + seq_printf(seq, "Root %d group %s\n", + c->root->hierarchy_id, name); } rcu_read_unlock(); read_unlock(&css_set_lock); |