diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 1107 |
1 files changed, 804 insertions, 303 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index cd83d9933b6..7ccba4bc5e3 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -23,6 +23,7 @@ */ #include <linux/cgroup.h> +#include <linux/ctype.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/kernel.h> @@ -48,6 +49,8 @@ #include <linux/namei.h> #include <linux/smp_lock.h> #include <linux/pid_namespace.h> +#include <linux/idr.h> +#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ #include <asm/atomic.h> @@ -60,6 +63,8 @@ static struct cgroup_subsys *subsys[] = { #include <linux/cgroup_subsys.h> }; +#define MAX_CGROUP_ROOT_NAMELEN 64 + /* * A cgroupfs_root represents the root of a cgroup hierarchy, * and may be associated with a superblock to form an active @@ -74,6 +79,9 @@ 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; @@ -94,6 +102,9 @@ struct cgroupfs_root { /* The path to use for release notifications. */ char release_agent_path[PATH_MAX]; + + /* The name for this hierarchy - may be empty */ + char name[MAX_CGROUP_ROOT_NAMELEN]; }; /* @@ -141,6 +152,10 @@ 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) @@ -201,6 +216,7 @@ struct cg_cgroup_link { * cgroup, anchored on cgroup->css_sets */ struct list_head cgrp_link_list; + struct cgroup *cgrp; /* * List running through cg_cgroup_links pointing at a * single css_set object, anchored on css_set->cg_links @@ -227,8 +243,11 @@ static int cgroup_subsys_init_idr(struct cgroup_subsys *ss); static DEFINE_RWLOCK(css_set_lock); static int css_set_count; -/* hash table for cgroup groups. This improves the performance to - * find an existing css_set */ +/* + * hash table for cgroup groups. This improves the performance to find + * an existing css_set. This hash doesn't (currently) take into + * account cgroups in empty hierarchies. + */ #define CSS_SET_HASH_BITS 7 #define CSS_SET_TABLE_SIZE (1 << CSS_SET_HASH_BITS) static struct hlist_head css_set_table[CSS_SET_TABLE_SIZE]; @@ -248,48 +267,22 @@ static struct hlist_head *css_set_hash(struct cgroup_subsys_state *css[]) return &css_set_table[index]; } +static void free_css_set_rcu(struct rcu_head *obj) +{ + struct css_set *cg = container_of(obj, struct css_set, rcu_head); + kfree(cg); +} + /* We don't maintain the lists running through each css_set to its * task until after the first call to cgroup_iter_start(). This * reduces the fork()/exit() overhead for people who have cgroups * 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 @@ -302,21 +295,28 @@ 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(); - kfree(cg); + + write_unlock(&css_set_lock); + call_rcu(&cg->rcu_head, free_css_set_rcu); } /* @@ -338,6 +338,78 @@ static inline void put_css_set_taskexit(struct css_set *cg) } /* + * compare_css_sets - helper function for find_existing_css_set(). + * @cg: candidate css_set being tested + * @old_cg: existing css_set for a task + * @new_cgrp: cgroup that's being entered by the task + * @template: desired set of css pointers in css_set (pre-calculated) + * + * Returns true if "cg" matches "old_cg" except for the hierarchy + * which "new_cgrp" belongs to, for which it should match "new_cgrp". + */ +static bool compare_css_sets(struct css_set *cg, + struct css_set *old_cg, + struct cgroup *new_cgrp, + struct cgroup_subsys_state *template[]) +{ + struct list_head *l1, *l2; + + if (memcmp(template, cg->subsys, sizeof(cg->subsys))) { + /* Not all subsystems matched */ + return false; + } + + /* + * Compare cgroup pointers in order to distinguish between + * different cgroups in heirarchies with no subsystems. We + * could get by with just this check alone (and skip the + * memcmp above) but on most setups the memcmp check will + * avoid the need for this more expensive check on almost all + * candidates. + */ + + l1 = &cg->cg_links; + l2 = &old_cg->cg_links; + while (1) { + struct cg_cgroup_link *cgl1, *cgl2; + struct cgroup *cg1, *cg2; + + l1 = l1->next; + l2 = l2->next; + /* See if we reached the end - both lists are equal length. */ + if (l1 == &cg->cg_links) { + BUG_ON(l2 != &old_cg->cg_links); + break; + } else { + BUG_ON(l2 == &old_cg->cg_links); + } + /* Locate the cgroups associated with these links. */ + cgl1 = list_entry(l1, struct cg_cgroup_link, cg_link_list); + cgl2 = list_entry(l2, struct cg_cgroup_link, cg_link_list); + cg1 = cgl1->cgrp; + cg2 = cgl2->cgrp; + /* Hierarchies should be linked in the same order. */ + BUG_ON(cg1->root != cg2->root); + + /* + * If this hierarchy is the hierarchy of the cgroup + * that's changing, then we need to check that this + * css_set points to the new cgroup; if it's any other + * hierarchy, then this css_set should point to the + * same cgroup as the old css_set. + */ + if (cg1->root == new_cgrp->root) { + if (cg1 != new_cgrp) + return false; + } else { + if (cg1 != cg2) + return false; + } + } + return true; +} + +/* * find_existing_css_set() is a helper for * find_css_set(), and checks to see whether an existing * css_set is suitable. @@ -378,10 +450,11 @@ static struct css_set *find_existing_css_set( hhead = css_set_hash(template); hlist_for_each_entry(cg, node, hhead, hlist) { - if (!memcmp(template, cg->subsys, sizeof(cg->subsys))) { - /* All subsystems matched */ - return cg; - } + if (!compare_css_sets(cg, oldcg, cgrp, template)) + continue; + + /* This css_set matches what we need */ + return cg; } /* No existing cgroup group matched */ @@ -435,8 +508,14 @@ static void link_css_set(struct list_head *tmp_cg_links, link = list_first_entry(tmp_cg_links, struct cg_cgroup_link, cgrp_link_list); link->cg = cg; + link->cgrp = cgrp; + atomic_inc(&cgrp->count); list_move(&link->cgrp_link_list, &cgrp->css_sets); - list_add(&link->cg_link_list, &cg->cg_links); + /* + * Always add links to the tail of the list so that the list + * is sorted by order of hierarchy creation + */ + list_add_tail(&link->cg_link_list, &cg->cg_links); } /* @@ -451,11 +530,11 @@ 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; struct hlist_head *hhead; + struct cg_cgroup_link *link; /* First see if we already have a cgroup group that matches * the desired set */ @@ -489,20 +568,12 @@ 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; - struct cgroup_subsys *ss = subsys[i]; - atomic_inc(&cgrp->count); - /* - * We want to add a link once per cgroup, so we - * only do it for the first subsystem in each - * hierarchy - */ - if (ss->root->subsys_list.next == &ss->sibling) - link_css_set(&tmp_cg_links, res, cgrp); + list_for_each_entry(link, &oldcg->cg_links, cg_link_list) { + struct cgroup *c = link->cgrp; + if (c->root == cgrp->root) + c = cgrp; + link_css_set(&tmp_cg_links, res, c); } - if (list_empty(&rootnode.subsys_list)) - link_css_set(&tmp_cg_links, res, dummytop); BUG_ON(!list_empty(&tmp_cg_links)); @@ -518,6 +589,41 @@ static struct css_set *find_css_set( } /* + * Return the cgroup for "task" from the given hierarchy. Must be + * called with cgroup_mutex held. + */ +static struct cgroup *task_cgroup_from_root(struct task_struct *task, + struct cgroupfs_root *root) +{ + struct css_set *css; + struct cgroup *res = NULL; + + BUG_ON(!mutex_is_locked(&cgroup_mutex)); + read_lock(&css_set_lock); + /* + * No need to lock the task - since we hold cgroup_mutex the + * task can't change groups, so the only thing that can happen + * is that it exits and its css is set back to init_css_set. + */ + css = task->cgroups; + if (css == &init_css_set) { + res = &root->top_cgroup; + } else { + struct cg_cgroup_link *link; + list_for_each_entry(link, &css->cg_links, cg_link_list) { + struct cgroup *c = link->cgrp; + if (c->root == root) { + res = c; + break; + } + } + } + read_unlock(&css_set_lock); + BUG_ON(!res); + return res; +} + +/* * There is one global cgroup mutex. We also require taking * task_lock() when dereferencing a task's cgroup subsys pointers. * See "The task_lock() exception", at the end of this comment. @@ -677,6 +783,12 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode) */ deactivate_super(cgrp->root->sb); + /* + * if we're getting rid of the cgroup, refcount should ensure + * that there are no pidlists left. + */ + BUG_ON(!list_empty(&cgrp->pidlists)); + call_rcu(&cgrp->rcu_head, free_cgroup_rcu); } iput(inode); @@ -841,6 +953,8 @@ static int cgroup_show_options(struct seq_file *seq, struct vfsmount *vfs) seq_puts(seq, ",noprefix"); if (strlen(root->release_agent_path)) seq_printf(seq, ",release_agent=%s", root->release_agent_path); + if (strlen(root->name)) + seq_printf(seq, ",name=%s", root->name); mutex_unlock(&cgroup_mutex); return 0; } @@ -849,6 +963,12 @@ struct cgroup_sb_opts { unsigned long subsys_bits; 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 @@ -863,9 +983,7 @@ static int parse_cgroupfs_options(char *data, mask = ~(1UL << cpuset_subsys_id); #endif - opts->subsys_bits = 0; - opts->flags = 0; - opts->release_agent = NULL; + memset(opts, 0, sizeof(*opts)); while ((token = strsep(&o, ",")) != NULL) { if (!*token) @@ -879,17 +997,42 @@ 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)) { /* Specifying two release agents is forbidden */ if (opts->release_agent) return -EINVAL; - opts->release_agent = kzalloc(PATH_MAX, GFP_KERNEL); + opts->release_agent = + kstrndup(token + 14, PATH_MAX, GFP_KERNEL); if (!opts->release_agent) return -ENOMEM; - strncpy(opts->release_agent, token + 14, PATH_MAX - 1); - opts->release_agent[PATH_MAX - 1] = 0; + } else if (!strncmp(token, "name=", 5)) { + int i; + const char *name = token + 5; + /* Can't specify an empty name */ + if (!strlen(name)) + return -EINVAL; + /* Must match [\w.-]+ */ + for (i = 0; i < strlen(name); i++) { + char c = name[i]; + if (isalnum(c)) + continue; + if ((c == '.') || (c == '-') || (c == '_')) + continue; + return -EINVAL; + } + /* Specifying two names is forbidden */ + if (opts->name) + return -EINVAL; + opts->name = kstrndup(name, + MAX_CGROUP_ROOT_NAMELEN, + GFP_KERNEL); + if (!opts->name) + return -ENOMEM; } else { struct cgroup_subsys *ss; int i; @@ -906,6 +1049,8 @@ 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 @@ -915,8 +1060,16 @@ static int parse_cgroupfs_options(char *data, (opts->subsys_bits & mask)) return -EINVAL; - /* We can't have an empty hierarchy */ - if (!opts->subsys_bits) + + /* 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; return 0; @@ -944,6 +1097,12 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) goto out_unlock; } + /* Don't allow name to change at remount */ + if (opts.name && strcmp(opts.name, root->name)) { + ret = -EINVAL; + goto out_unlock; + } + ret = rebind_subsystems(root, opts.subsys_bits); if (ret) goto out_unlock; @@ -955,6 +1114,7 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) strcpy(root->release_agent_path, opts.release_agent); out_unlock: kfree(opts.release_agent); + kfree(opts.name); mutex_unlock(&cgroup_mutex); mutex_unlock(&cgrp->dentry->d_inode->i_mutex); unlock_kernel(); @@ -974,9 +1134,10 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->children); INIT_LIST_HEAD(&cgrp->css_sets); INIT_LIST_HEAD(&cgrp->release_list); - INIT_LIST_HEAD(&cgrp->pids_list); - init_rwsem(&cgrp->pids_mutex); + INIT_LIST_HEAD(&cgrp->pidlists); + mutex_init(&cgrp->pidlist_mutex); } + static void init_cgroup_root(struct cgroupfs_root *root) { struct cgroup *cgrp = &root->top_cgroup; @@ -988,33 +1149,106 @@ 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 cgroupfs_root *new = data; + struct cgroup_sb_opts *opts = data; struct cgroupfs_root *root = sb->s_fs_info; - /* First check subsystems */ - if (new->subsys_bits != root->subsys_bits) - return 0; + /* If we asked for a name then it must match */ + if (opts->name && strcmp(opts->name, root->name)) + return 0; - /* Next check flags */ - if (new->flags != root->flags) + /* + * 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; } +static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) +{ + struct cgroupfs_root *root; + + 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) + strcpy(root->release_agent_path, opts->release_agent); + if (opts->name) + strcpy(root->name, opts->name); + 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; - struct cgroupfs_root *root = data; + struct cgroup_sb_opts *opts = data; + + /* If we don't have a new root, we can't set up a new sb */ + if (!opts->new_root) + return -EINVAL; + + BUG_ON(!opts->subsys_bits && !opts->none); ret = set_anon_super(sb, NULL); if (ret) return ret; - sb->s_fs_info = root; - root->sb = sb; + sb->s_fs_info = opts->new_root; + opts->new_root->sb = sb; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; @@ -1051,48 +1285,43 @@ static int cgroup_get_sb(struct file_system_type *fs_type, void *data, struct vfsmount *mnt) { struct cgroup_sb_opts opts; + struct cgroupfs_root *root; int ret = 0; struct super_block *sb; - struct cgroupfs_root *root; - struct list_head tmp_cg_links; + struct cgroupfs_root *new_root; /* First find the desired set of subsystems */ ret = parse_cgroupfs_options(data, &opts); - if (ret) { - kfree(opts.release_agent); - return ret; - } - - root = kzalloc(sizeof(*root), GFP_KERNEL); - if (!root) { - kfree(opts.release_agent); - return -ENOMEM; - } + if (ret) + goto out_err; - init_cgroup_root(root); - root->subsys_bits = opts.subsys_bits; - root->flags = opts.flags; - if (opts.release_agent) { - strcpy(root->release_agent_path, opts.release_agent); - kfree(opts.release_agent); + /* + * Allocate a new cgroup root. We may not need it if we're + * reusing an existing hierarchy. + */ + new_root = cgroup_root_from_opts(&opts); + if (IS_ERR(new_root)) { + ret = PTR_ERR(new_root); + goto out_err; } + opts.new_root = new_root; - sb = sget(fs_type, cgroup_test_super, cgroup_set_super, root); - + /* Locate an existing or new sb for this hierarchy */ + sb = sget(fs_type, cgroup_test_super, cgroup_set_super, &opts); if (IS_ERR(sb)) { - kfree(root); - return PTR_ERR(sb); + ret = PTR_ERR(sb); + cgroup_drop_root(opts.new_root); + goto out_err; } - if (sb->s_fs_info != root) { - /* Reusing an existing superblock */ - BUG_ON(sb->s_root == NULL); - kfree(root); - root = NULL; - } else { - /* New superblock */ + root = sb->s_fs_info; + BUG_ON(!root); + if (root == opts.new_root) { + /* We used the new root structure, so this is a new hierarchy */ + struct list_head tmp_cg_links; struct cgroup *root_cgrp = &root->top_cgroup; struct inode *inode; + struct cgroupfs_root *existing_root; int i; BUG_ON(sb->s_root != NULL); @@ -1105,6 +1334,18 @@ static int cgroup_get_sb(struct file_system_type *fs_type, mutex_lock(&inode->i_mutex); mutex_lock(&cgroup_mutex); + if (strlen(root->name)) { + /* Check for name clashes with existing mounts */ + for_each_active_root(existing_root) { + if (!strcmp(existing_root->name, root->name)) { + ret = -EBUSY; + mutex_unlock(&cgroup_mutex); + mutex_unlock(&inode->i_mutex); + goto drop_new_super; + } + } + } + /* * We're accessing css_set_count without locking * css_set_lock here, but that's OK - it can only be @@ -1123,7 +1364,8 @@ static int cgroup_get_sb(struct file_system_type *fs_type, if (ret == -EBUSY) { mutex_unlock(&cgroup_mutex); mutex_unlock(&inode->i_mutex); - goto free_cg_links; + free_cg_links(&tmp_cg_links); + goto drop_new_super; } /* EBUSY should be the only error here */ @@ -1155,17 +1397,27 @@ static int cgroup_get_sb(struct file_system_type *fs_type, BUG_ON(root->number_of_cgroups != 1); cgroup_populate_dir(root_cgrp); - mutex_unlock(&inode->i_mutex); mutex_unlock(&cgroup_mutex); + mutex_unlock(&inode->i_mutex); + } else { + /* + * We re-used an existing hierarchy - the new root (if + * any) is not needed + */ + cgroup_drop_root(opts.new_root); } simple_set_mnt(mnt, sb); + kfree(opts.release_agent); + kfree(opts.name); return 0; - free_cg_links: - free_cg_links(&tmp_cg_links); drop_new_super: deactivate_locked_super(sb); + out_err: + kfree(opts.release_agent); + kfree(opts.name); + return ret; } @@ -1211,7 +1463,7 @@ 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 = { @@ -1276,27 +1528,6 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) return 0; } -/* - * Return the first subsystem attached to a cgroup's hierarchy, and - * its subsystem id. - */ - -static void get_first_subsys(const struct cgroup *cgrp, - struct cgroup_subsys_state **css, int *subsys_id) -{ - const struct cgroupfs_root *root = cgrp->root; - const struct cgroup_subsys *test_ss; - BUG_ON(list_empty(&root->subsys_list)); - test_ss = list_entry(root->subsys_list.next, - struct cgroup_subsys, sibling); - if (css) { - *css = cgrp->subsys[test_ss->subsys_id]; - BUG_ON(!*css); - } - if (subsys_id) - *subsys_id = test_ss->subsys_id; -} - /** * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' * @cgrp: the cgroup the task is attaching to @@ -1313,18 +1544,15 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) struct css_set *cg; struct css_set *newcg; struct cgroupfs_root *root = cgrp->root; - int subsys_id; - - get_first_subsys(cgrp, NULL, &subsys_id); /* Nothing to do if the task is already in that cgroup */ - oldcgrp = task_cgroup(tsk, subsys_id); + oldcgrp = task_cgroup_from_root(tsk, root); if (cgrp == oldcgrp) return 0; for_each_subsys(root, ss) { if (ss->can_attach) { - retval = ss->can_attach(ss, cgrp, tsk); + retval = ss->can_attach(ss, cgrp, tsk, false); if (retval) return retval; } @@ -1362,7 +1590,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) for_each_subsys(root, ss) { if (ss->attach) - ss->attach(ss, cgrp, oldcgrp, tsk); + ss->attach(ss, cgrp, oldcgrp, tsk, false); } set_bit(CGRP_RELEASABLE, &oldcgrp->flags); synchronize_rcu(); @@ -1423,15 +1651,6 @@ static int cgroup_tasks_write(struct cgroup *cgrp, struct cftype *cft, u64 pid) return ret; } -/* The various types of files and directories in a cgroup file system */ -enum cgroup_filetype { - FILE_ROOT, - FILE_DIR, - FILE_TASKLIST, - FILE_NOTIFY_ON_RELEASE, - FILE_RELEASE_AGENT, -}; - /** * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. * @cgrp: the cgroup to be checked for liveness @@ -1876,7 +2095,7 @@ int cgroup_task_count(const struct cgroup *cgrp) * the start of a css_set */ static void cgroup_advance_iter(struct cgroup *cgrp, - struct cgroup_iter *it) + struct cgroup_iter *it) { struct list_head *l = it->cg_link; struct cg_cgroup_link *link; @@ -2129,7 +2348,7 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) } /* - * Stuff for reading the 'tasks' file. + * Stuff for reading the 'tasks'/'procs' files. * * Reading this file can return large amounts of data if a cgroup has * *lots* of attached tasks. So it may need several calls to read(), @@ -2139,27 +2358,196 @@ int cgroup_scan_tasks(struct cgroup_scanner *scan) */ /* - * Load into 'pidarray' up to 'npids' of the tasks using cgroup - * 'cgrp'. Return actual number of pids loaded. No need to - * task_lock(p) when reading out p->cgroup, since we're in an RCU - * read section, so the css_set can't go away, and is - * immutable after creation. + * The following two functions "fix" the issue where there are more pids + * than kmalloc will give memory for; in such cases, we use vmalloc/vfree. + * TODO: replace with a kernel-wide solution to this problem + */ +#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) +static void *pidlist_allocate(int count) +{ + if (PIDLIST_TOO_LARGE(count)) + return vmalloc(count * sizeof(pid_t)); + else + return kmalloc(count * sizeof(pid_t), GFP_KERNEL); +} +static void pidlist_free(void *p) +{ + if (is_vmalloc_addr(p)) + vfree(p); + else + kfree(p); +} +static void *pidlist_resize(void *p, int newcount) +{ + void *newlist; + /* note: if new alloc fails, old p will still be valid either way */ + if (is_vmalloc_addr(p)) { + newlist = vmalloc(newcount * sizeof(pid_t)); + if (!newlist) + return NULL; + memcpy(newlist, p, newcount * sizeof(pid_t)); + vfree(p); + } else { + newlist = krealloc(p, newcount * sizeof(pid_t), GFP_KERNEL); + } + return newlist; +} + +/* + * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries + * If the new stripped list is sufficiently smaller and there's enough memory + * to allocate a new buffer, will let go of the unneeded memory. Returns the + * number of unique elements. + */ +/* is the size difference enough that we should re-allocate the array? */ +#define PIDLIST_REALLOC_DIFFERENCE(old, new) ((old) - PAGE_SIZE >= (new)) +static int pidlist_uniq(pid_t **p, int length) +{ + int src, dest = 1; + pid_t *list = *p; + pid_t *newlist; + + /* + * we presume the 0th element is unique, so i starts at 1. trivial + * edge cases first; no work needs to be done for either + */ + if (length == 0 || length == 1) + return length; + /* src and dest walk down the list; dest counts unique elements */ + for (src = 1; src < length; src++) { + /* find next unique element */ + while (list[src] == list[src-1]) { + src++; + if (src == length) + goto after; + } + /* dest always points to where the next unique element goes */ + list[dest] = list[src]; + dest++; + } +after: + /* + * if the length difference is large enough, we want to allocate a + * smaller buffer to save memory. if this fails due to out of memory, + * we'll just stay with what we've got. + */ + if (PIDLIST_REALLOC_DIFFERENCE(length, dest)) { + newlist = pidlist_resize(list, dest); + if (newlist) + *p = newlist; + } + return dest; +} + +static int cmppid(const void *a, const void *b) +{ + return *(pid_t *)a - *(pid_t *)b; +} + +/* + * find the appropriate pidlist for our purpose (given procs vs tasks) + * returns with the lock on that pidlist already held, and takes care + * of the use count, or returns NULL with no locks held if we're out of + * memory. */ -static int pid_array_load(pid_t *pidarray, int npids, struct cgroup *cgrp) +static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, + enum cgroup_filetype type) { - int n = 0, pid; + struct cgroup_pidlist *l; + /* don't need task_nsproxy() if we're looking at ourself */ + struct pid_namespace *ns = get_pid_ns(current->nsproxy->pid_ns); + /* + * We can't drop the pidlist_mutex before taking the l->mutex in case + * the last ref-holder is trying to remove l from the list at the same + * time. Holding the pidlist_mutex precludes somebody taking whichever + * list we find out from under us - compare release_pid_array(). + */ + mutex_lock(&cgrp->pidlist_mutex); + list_for_each_entry(l, &cgrp->pidlists, links) { + if (l->key.type == type && l->key.ns == ns) { + /* found a matching list - drop the extra refcount */ + put_pid_ns(ns); + /* make sure l doesn't vanish out from under us */ + down_write(&l->mutex); + mutex_unlock(&cgrp->pidlist_mutex); + l->use_count++; + return l; + } + } + /* entry not found; create a new one */ + l = kmalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); + if (!l) { + mutex_unlock(&cgrp->pidlist_mutex); + put_pid_ns(ns); + return l; + } + init_rwsem(&l->mutex); + down_write(&l->mutex); + l->key.type = type; + l->key.ns = ns; + l->use_count = 0; /* don't increment here */ + l->list = NULL; + l->owner = cgrp; + list_add(&l->links, &cgrp->pidlists); + mutex_unlock(&cgrp->pidlist_mutex); + return l; +} + +/* + * Load a cgroup's pidarray with either procs' tgids or tasks' pids + */ +static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, + struct cgroup_pidlist **lp) +{ + pid_t *array; + int length; + int pid, n = 0; /* used for populating the array */ struct cgroup_iter it; struct task_struct *tsk; + struct cgroup_pidlist *l; + + /* + * If cgroup gets more users after we read count, we won't have + * enough space - tough. This race is indistinguishable to the + * caller from the case that the additional cgroup users didn't + * show up until sometime later on. + */ + length = cgroup_task_count(cgrp); + array = pidlist_allocate(length); + if (!array) + return -ENOMEM; + /* now, populate the array */ cgroup_iter_start(cgrp, &it); while ((tsk = cgroup_iter_next(cgrp, &it))) { - if (unlikely(n == npids)) + if (unlikely(n == length)) break; - pid = task_pid_vnr(tsk); - if (pid > 0) - pidarray[n++] = pid; + /* get tgid or pid for procs or tasks file respectively */ + if (type == CGROUP_FILE_PROCS) + pid = task_tgid_vnr(tsk); + else + pid = task_pid_vnr(tsk); + if (pid > 0) /* make sure to only use valid results */ + array[n++] = pid; } cgroup_iter_end(cgrp, &it); - return n; + length = n; + /* now sort & (if procs) strip out duplicates */ + sort(array, length, sizeof(pid_t), cmppid, NULL); + if (type == CGROUP_FILE_PROCS) + length = pidlist_uniq(&array, length); + l = cgroup_pidlist_find(cgrp, type); + if (!l) { + pidlist_free(array); + return -ENOMEM; + } + /* store array, freeing old if necessary - lock already held */ + pidlist_free(l->list); + l->list = array; + l->length = length; + l->use_count++; + up_write(&l->mutex); + *lp = l; + return 0; } /** @@ -2216,37 +2604,14 @@ err: return ret; } -/* - * Cache pids for all threads in the same pid namespace that are - * opening the same "tasks" file. - */ -struct cgroup_pids { - /* The node in cgrp->pids_list */ - struct list_head list; - /* The cgroup those pids belong to */ - struct cgroup *cgrp; - /* The namepsace those pids belong to */ - struct pid_namespace *ns; - /* Array of process ids in the cgroup */ - pid_t *tasks_pids; - /* How many files are using the this tasks_pids array */ - int use_count; - /* Length of the current tasks_pids array */ - int length; -}; - -static int cmppid(const void *a, const void *b) -{ - return *(pid_t *)a - *(pid_t *)b; -} /* - * seq_file methods for the "tasks" file. The seq_file position is the + * seq_file methods for the tasks/procs files. The seq_file position is the * next pid to display; the seq_file iterator is a pointer to the pid - * in the cgroup->tasks_pids array. + * in the cgroup->l->list array. */ -static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos) +static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) { /* * Initially we receive a position value that corresponds to @@ -2254,48 +2619,45 @@ static void *cgroup_tasks_start(struct seq_file *s, loff_t *pos) * after a seek to the start). Use a binary-search to find the * next pid to display, if any */ - struct cgroup_pids *cp = s->private; - struct cgroup *cgrp = cp->cgrp; + struct cgroup_pidlist *l = s->private; int index = 0, pid = *pos; int *iter; - down_read(&cgrp->pids_mutex); + down_read(&l->mutex); if (pid) { - int end = cp->length; + int end = l->length; while (index < end) { int mid = (index + end) / 2; - if (cp->tasks_pids[mid] == pid) { + if (l->list[mid] == pid) { index = mid; break; - } else if (cp->tasks_pids[mid] <= pid) + } else if (l->list[mid] <= pid) index = mid + 1; else end = mid; } } /* If we're off the end of the array, we're done */ - if (index >= cp->length) + if (index >= l->length) return NULL; /* Update the abstract position to be the actual pid that we found */ - iter = cp->tasks_pids + index; + iter = l->list + index; *pos = *iter; return iter; } -static void cgroup_tasks_stop(struct seq_file *s, void *v) +static void cgroup_pidlist_stop(struct seq_file *s, void *v) { - struct cgroup_pids *cp = s->private; - struct cgroup *cgrp = cp->cgrp; - up_read(&cgrp->pids_mutex); + struct cgroup_pidlist *l = s->private; + up_read(&l->mutex); } -static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) +static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) { - struct cgroup_pids *cp = s->private; - int *p = v; - int *end = cp->tasks_pids + cp->length; - + struct cgroup_pidlist *l = s->private; + pid_t *p = v; + pid_t *end = l->list + l->length; /* * Advance to the next pid in the array. If this goes off the * end, we're done @@ -2309,124 +2671,107 @@ static void *cgroup_tasks_next(struct seq_file *s, void *v, loff_t *pos) } } -static int cgroup_tasks_show(struct seq_file *s, void *v) +static int cgroup_pidlist_show(struct seq_file *s, void *v) { return seq_printf(s, "%d\n", *(int *)v); } -static const struct seq_operations cgroup_tasks_seq_operations = { - .start = cgroup_tasks_start, - .stop = cgroup_tasks_stop, - .next = cgroup_tasks_next, - .show = cgroup_tasks_show, +/* + * seq_operations functions for iterating on pidlists through seq_file - + * independent of whether it's tasks or procs + */ +static const struct seq_operations cgroup_pidlist_seq_operations = { + .start = cgroup_pidlist_start, + .stop = cgroup_pidlist_stop, + .next = cgroup_pidlist_next, + .show = cgroup_pidlist_show, }; -static void release_cgroup_pid_array(struct cgroup_pids *cp) +static void cgroup_release_pid_array(struct cgroup_pidlist *l) { - struct cgroup *cgrp = cp->cgrp; - - down_write(&cgrp->pids_mutex); - BUG_ON(!cp->use_count); - if (!--cp->use_count) { - list_del(&cp->list); - put_pid_ns(cp->ns); - kfree(cp->tasks_pids); - kfree(cp); + /* + * the case where we're the last user of this particular pidlist will + * have us remove it from the cgroup's list, which entails taking the + * mutex. since in pidlist_find the pidlist->lock depends on cgroup-> + * pidlist_mutex, we have to take pidlist_mutex first. + */ + mutex_lock(&l->owner->pidlist_mutex); + down_write(&l->mutex); + BUG_ON(!l->use_count); + if (!--l->use_count) { + /* we're the last user if refcount is 0; remove and free */ + list_del(&l->links); + mutex_unlock(&l->owner->pidlist_mutex); + pidlist_free(l->list); + put_pid_ns(l->key.ns); + up_write(&l->mutex); + kfree(l); + return; } - up_write(&cgrp->pids_mutex); + mutex_unlock(&l->owner->pidlist_mutex); + up_write(&l->mutex); } -static int cgroup_tasks_release(struct inode *inode, struct file *file) +static int cgroup_pidlist_release(struct inode *inode, struct file *file) { - struct seq_file *seq; - struct cgroup_pids *cp; - + struct cgroup_pidlist *l; if (!(file->f_mode & FMODE_READ)) return 0; - - seq = file->private_data; - cp = seq->private; - - release_cgroup_pid_array(cp); + /* + * the seq_file will only be initialized if the file was opened for + * reading; hence we check if it's not null only in that case. + */ + l = ((struct seq_file *)file->private_data)->private; + cgroup_release_pid_array(l); return seq_release(inode, file); } -static struct file_operations cgroup_tasks_operations = { +static const struct file_operations cgroup_pidlist_operations = { .read = seq_read, .llseek = seq_lseek, .write = cgroup_file_write, - .release = cgroup_tasks_release, + .release = cgroup_pidlist_release, }; /* - * Handle an open on 'tasks' file. Prepare an array containing the - * process id's of tasks currently attached to the cgroup being opened. + * The following functions handle opens on a file that displays a pidlist + * (tasks or procs). Prepare an array of the process/thread IDs of whoever's + * in the cgroup. */ - -static int cgroup_tasks_open(struct inode *unused, struct file *file) +/* helper function for the two below it */ +static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) { struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent); - struct pid_namespace *ns = current->nsproxy->pid_ns; - struct cgroup_pids *cp; - pid_t *pidarray; - int npids; + struct cgroup_pidlist *l; int retval; /* Nothing to do for write-only files */ if (!(file->f_mode & FMODE_READ)) return 0; - /* - * If cgroup gets more users after we read count, we won't have - * enough space - tough. This race is indistinguishable to the - * caller from the case that the additional cgroup users didn't - * show up until sometime later on. - */ - npids = cgroup_task_count(cgrp); - pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL); - if (!pidarray) - return -ENOMEM; - npids = pid_array_load(pidarray, npids, cgrp); - sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); - - /* - * Store the array in the cgroup, freeing the old - * array if necessary - */ - down_write(&cgrp->pids_mutex); - - list_for_each_entry(cp, &cgrp->pids_list, list) { - if (ns == cp->ns) - goto found; - } - - cp = kzalloc(sizeof(*cp), GFP_KERNEL); - if (!cp) { - up_write(&cgrp->pids_mutex); - kfree(pidarray); - return -ENOMEM; - } - cp->cgrp = cgrp; - cp->ns = ns; - get_pid_ns(ns); - list_add(&cp->list, &cgrp->pids_list); -found: - kfree(cp->tasks_pids); - cp->tasks_pids = pidarray; - cp->length = npids; - cp->use_count++; - up_write(&cgrp->pids_mutex); - - file->f_op = &cgroup_tasks_operations; + /* have the array populated */ + retval = pidlist_array_load(cgrp, type, &l); + if (retval) + return retval; + /* configure file information */ + file->f_op = &cgroup_pidlist_operations; - retval = seq_open(file, &cgroup_tasks_seq_operations); + retval = seq_open(file, &cgroup_pidlist_seq_operations); if (retval) { - release_cgroup_pid_array(cp); + cgroup_release_pid_array(l); return retval; } - ((struct seq_file *)file->private_data)->private = cp; + ((struct seq_file *)file->private_data)->private = l; return 0; } +static int cgroup_tasks_open(struct inode *unused, struct file *file) +{ + return cgroup_pidlist_open(file, CGROUP_FILE_TASKS); +} +static int cgroup_procs_open(struct inode *unused, struct file *file) +{ + return cgroup_pidlist_open(file, CGROUP_FILE_PROCS); +} static u64 cgroup_read_notify_on_release(struct cgroup *cgrp, struct cftype *cft) @@ -2449,21 +2794,27 @@ static int cgroup_write_notify_on_release(struct cgroup *cgrp, /* * for the common functions, 'private' gives the type of file */ +/* for hysterical raisins, we can't put this on the older files */ +#define CGROUP_FILE_GENERIC_PREFIX "cgroup." static struct cftype files[] = { { .name = "tasks", .open = cgroup_tasks_open, .write_u64 = cgroup_tasks_write, - .release = cgroup_tasks_release, - .private = FILE_TASKLIST, + .release = cgroup_pidlist_release, .mode = S_IRUGO | S_IWUSR, }, - + { + .name = CGROUP_FILE_GENERIC_PREFIX "procs", + .open = cgroup_procs_open, + /* .write_u64 = cgroup_procs_write, TODO */ + .release = cgroup_pidlist_release, + .mode = S_IRUGO, + }, { .name = "notify_on_release", .read_u64 = cgroup_read_notify_on_release, .write_u64 = cgroup_write_notify_on_release, - .private = FILE_NOTIFY_ON_RELEASE, }, }; @@ -2472,7 +2823,6 @@ static struct cftype cft_release_agent = { .read_seq_string = cgroup_release_agent_show, .write_string = cgroup_release_agent_write, .max_write_len = PATH_MAX, - .private = FILE_RELEASE_AGENT, }; static int cgroup_populate_dir(struct cgroup *cgrp) @@ -2879,6 +3229,7 @@ int __init cgroup_init_early(void) init_task.cgroups = &init_css_set; init_css_set_link.cg = &init_css_set; + init_css_set_link.cgrp = dummytop; list_add(&init_css_set_link.cgrp_link_list, &rootnode.top_cgroup.css_sets); list_add(&init_css_set_link.cg_link_list, @@ -2933,7 +3284,7 @@ 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; @@ -2986,15 +3337,16 @@ static int proc_cgroup_show(struct seq_file *m, void *v) for_each_active_root(root) { struct cgroup_subsys *ss; struct cgroup *cgrp; - int subsys_id; 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)) + seq_printf(m, "%sname=%s", count ? "," : "", + root->name); seq_putc(m, ':'); - get_first_subsys(&root->top_cgroup, NULL, &subsys_id); - cgrp = task_cgroup(tsk, subsys_id); + cgrp = task_cgroup_from_root(tsk, root); retval = cgroup_path(cgrp, buf, PAGE_SIZE); if (retval < 0) goto out_unlock; @@ -3033,8 +3385,8 @@ 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); @@ -3320,13 +3672,11 @@ int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task) { int ret; struct cgroup *target; - int subsys_id; if (cgrp == dummytop) return 1; - get_first_subsys(cgrp, NULL, &subsys_id); - target = task_cgroup(task, subsys_id); + target = task_cgroup_from_root(task, cgrp->root); while (cgrp != target && cgrp!= cgrp->top_cgroup) cgrp = cgrp->parent; ret = (cgrp == target); @@ -3693,3 +4043,154 @@ css_get_next(struct cgroup_subsys *ss, int id, return ret; } +#ifdef CONFIG_CGROUP_DEBUG +static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss, + struct cgroup *cont) +{ + struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); + + if (!css) + return ERR_PTR(-ENOMEM); + + return css; +} + +static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont) +{ + kfree(cont->subsys[debug_subsys_id]); +} + +static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft) +{ + return atomic_read(&cont->count); +} + +static u64 debug_taskcount_read(struct cgroup *cont, struct cftype *cft) +{ + return cgroup_task_count(cont); +} + +static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft) +{ + return (u64)(unsigned long)current->cgroups; +} + +static u64 current_css_set_refcount_read(struct cgroup *cont, + struct cftype *cft) +{ + u64 count; + + rcu_read_lock(); + count = atomic_read(¤t->cgroups->refcount); + rcu_read_unlock(); + return count; +} + +static int current_css_set_cg_links_read(struct cgroup *cont, + struct cftype *cft, + struct seq_file *seq) +{ + struct cg_cgroup_link *link; + struct css_set *cg; + + read_lock(&css_set_lock); + rcu_read_lock(); + cg = rcu_dereference(current->cgroups); + list_for_each_entry(link, &cg->cg_links, cg_link_list) { + struct cgroup *c = link->cgrp; + const char *name; + + if (c->dentry) + name = c->dentry->d_name.name; + else + name = "?"; + seq_printf(seq, "Root %d group %s\n", + c->root->hierarchy_id, name); + } + rcu_read_unlock(); + read_unlock(&css_set_lock); + return 0; +} + +#define MAX_TASKS_SHOWN_PER_CSS 25 +static int cgroup_css_links_read(struct cgroup *cont, + struct cftype *cft, + struct seq_file *seq) +{ + struct cg_cgroup_link *link; + + read_lock(&css_set_lock); + list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { + struct css_set *cg = link->cg; + struct task_struct *task; + int count = 0; + seq_printf(seq, "css_set %p\n", cg); + list_for_each_entry(task, &cg->tasks, cg_list) { + if (count++ > MAX_TASKS_SHOWN_PER_CSS) { + seq_puts(seq, " ...\n"); + break; + } else { + seq_printf(seq, " task %d\n", + task_pid_vnr(task)); + } + } + } + read_unlock(&css_set_lock); + return 0; +} + +static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft) +{ + return test_bit(CGRP_RELEASABLE, &cgrp->flags); +} + +static struct cftype debug_files[] = { + { + .name = "cgroup_refcount", + .read_u64 = cgroup_refcount_read, + }, + { + .name = "taskcount", + .read_u64 = debug_taskcount_read, + }, + + { + .name = "current_css_set", + .read_u64 = current_css_set_read, + }, + + { + .name = "current_css_set_refcount", + .read_u64 = current_css_set_refcount_read, + }, + + { + .name = "current_css_set_cg_links", + .read_seq_string = current_css_set_cg_links_read, + }, + + { + .name = "cgroup_css_links", + .read_seq_string = cgroup_css_links_read, + }, + + { + .name = "releasable", + .read_u64 = releasable_read, + }, +}; + +static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont) +{ + return cgroup_add_files(cont, ss, debug_files, + ARRAY_SIZE(debug_files)); +} + +struct cgroup_subsys debug_subsys = { + .name = "debug", + .create = debug_create, + .destroy = debug_destroy, + .populate = debug_populate, + .subsys_id = debug_subsys_id, +}; +#endif /* CONFIG_CGROUP_DEBUG */ |