diff options
| -rw-r--r-- | include/linux/cgroup.h | 33 | ||||
| -rw-r--r-- | kernel/cgroup.c | 132 |
2 files changed, 162 insertions, 3 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index ad2a14680b7f..af6211c7a42b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -192,6 +192,7 @@ struct cgroup { struct list_head css_sets; struct list_head allcg_node; /* cgroupfs_root->allcg_list */ + struct list_head cft_q_node; /* used during cftype add/rm */ /* * Linked list running through all cgroups that can @@ -277,11 +278,17 @@ struct cgroup_map_cb { * - the 'cftype' of the file is file->f_dentry->d_fsdata */ -#define MAX_CFTYPE_NAME 64 +/* cftype->flags */ +#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */ +#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create onp root cg */ + +#define MAX_CFTYPE_NAME 64 + struct cftype { /* * By convention, the name should begin with the name of the - * subsystem, followed by a period + * subsystem, followed by a period. Zero length string indicates + * end of cftype array. */ char name[MAX_CFTYPE_NAME]; int private; @@ -297,6 +304,9 @@ struct cftype { */ size_t max_write_len; + /* CFTYPE_* flags */ + unsigned int flags; + int (*open)(struct inode *inode, struct file *file); ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, struct file *file, @@ -375,6 +385,16 @@ struct cftype { struct eventfd_ctx *eventfd); }; +/* + * cftype_sets describe cftypes belonging to a subsystem and are chained at + * cgroup_subsys->cftsets. Each cftset points to an array of cftypes + * terminated by zero length name. + */ +struct cftype_set { + struct list_head node; /* chained at subsys->cftsets */ + const struct cftype *cfts; +}; + struct cgroup_scanner { struct cgroup *cg; int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); @@ -400,6 +420,8 @@ int cgroup_add_files(struct cgroup *cgrp, const struct cftype cft[], int count); +int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts); + int cgroup_is_removed(const struct cgroup *cgrp); int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); @@ -502,6 +524,13 @@ struct cgroup_subsys { struct idr idr; spinlock_t id_lock; + /* list of cftype_sets */ + struct list_head cftsets; + + /* base cftypes, automatically [de]registered with subsys itself */ + struct cftype *base_cftypes; + struct cftype_set base_cftset; + /* should be defined only by modular subsystems */ struct module *module; }; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index db4319c030d0..df8fb82ef350 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2623,8 +2623,14 @@ int cgroup_add_file(struct cgroup *cgrp, struct dentry *dentry; int error; umode_t mode; - char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 }; + + /* does @cft->flags tell us to skip creation on @cgrp? */ + if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent) + return 0; + if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent) + return 0; + if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) { strcpy(name, subsys->name); strcat(name, "."); @@ -2660,6 +2666,95 @@ int cgroup_add_files(struct cgroup *cgrp, } EXPORT_SYMBOL_GPL(cgroup_add_files); +static DEFINE_MUTEX(cgroup_cft_mutex); + +static void cgroup_cfts_prepare(void) + __acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex) +{ + /* + * Thanks to the entanglement with vfs inode locking, we can't walk + * the existing cgroups under cgroup_mutex and create files. + * Instead, we increment reference on all cgroups and build list of + * them using @cgrp->cft_q_node. Grab cgroup_cft_mutex to ensure + * exclusive access to the field. + */ + mutex_lock(&cgroup_cft_mutex); + mutex_lock(&cgroup_mutex); +} + +static void cgroup_cfts_commit(struct cgroup_subsys *ss, + const struct cftype *cfts) + __releases(&cgroup_mutex) __releases(&cgroup_cft_mutex) +{ + LIST_HEAD(pending); + struct cgroup *cgrp, *n; + int count = 0; + + while (cfts[count].name[0] != '\0') + count++; + + /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ + if (cfts && ss->root != &rootnode) { + list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) { + dget(cgrp->dentry); + list_add_tail(&cgrp->cft_q_node, &pending); + } + } + + mutex_unlock(&cgroup_mutex); + + /* + * All new cgroups will see @cfts update on @ss->cftsets. Add/rm + * files for all cgroups which were created before. + */ + list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) { + struct inode *inode = cgrp->dentry->d_inode; + + mutex_lock(&inode->i_mutex); + mutex_lock(&cgroup_mutex); + if (!cgroup_is_removed(cgrp)) + cgroup_add_files(cgrp, ss, cfts, count); + mutex_unlock(&cgroup_mutex); + mutex_unlock(&inode->i_mutex); + + list_del_init(&cgrp->cft_q_node); + dput(cgrp->dentry); + } + + mutex_unlock(&cgroup_cft_mutex); +} + +/** + * cgroup_add_cftypes - add an array of cftypes to a subsystem + * @ss: target cgroup subsystem + * @cfts: zero-length name terminated array of cftypes + * + * Register @cfts to @ss. Files described by @cfts are created for all + * existing cgroups to which @ss is attached and all future cgroups will + * have them too. This function can be called anytime whether @ss is + * attached or not. + * + * Returns 0 on successful registration, -errno on failure. Note that this + * function currently returns 0 as long as @cfts registration is successful + * even if some file creation attempts on existing cgroups fail. + */ +int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts) +{ + struct cftype_set *set; + + set = kzalloc(sizeof(*set), GFP_KERNEL); + if (!set) + return -ENOMEM; + + cgroup_cfts_prepare(); + set->cfts = cfts; + list_add_tail(&set->node, &ss->cftsets); + cgroup_cfts_commit(ss, cfts); + + return 0; +} +EXPORT_SYMBOL_GPL(cgroup_add_cftypes); + /** * cgroup_task_count - count the number of tasks in a cgroup. * @cgrp: the cgroup in question @@ -3660,10 +3755,25 @@ static int cgroup_populate_dir(struct cgroup *cgrp) return err; } + /* process cftsets of each subsystem */ for_each_subsys(cgrp->root, ss) { + struct cftype_set *set; + if (ss->populate && (err = ss->populate(ss, cgrp)) < 0) return err; + + list_for_each_entry(set, &ss->cftsets, node) { + const struct cftype *cft; + + for (cft = set->cfts; cft->name[0] != '\0'; cft++) { + err = cgroup_add_file(cgrp, ss, cft); + if (err) + pr_warning("cgroup_populate_dir: failed to create %s, err=%d\n", + cft->name, err); + } + } } + /* This cgroup is ready now */ for_each_subsys(cgrp->root, ss) { struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id]; @@ -4034,12 +4144,29 @@ again: return 0; } +static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss) +{ + INIT_LIST_HEAD(&ss->cftsets); + + /* + * base_cftset is embedded in subsys itself, no need to worry about + * deregistration. + */ + if (ss->base_cftypes) { + ss->base_cftset.cfts = ss->base_cftypes; + list_add_tail(&ss->base_cftset.node, &ss->cftsets); + } +} + static void __init cgroup_init_subsys(struct cgroup_subsys *ss) { struct cgroup_subsys_state *css; printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name); + /* init base cftset */ + cgroup_init_cftsets(ss); + /* Create the top cgroup state for this subsystem */ list_add(&ss->sibling, &rootnode.subsys_list); ss->root = &rootnode; @@ -4109,6 +4236,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) return 0; } + /* init base cftset */ + cgroup_init_cftsets(ss); + /* * need to register a subsys id before anything else - for example, * init_cgroup_css needs it. |