diff options
| -rw-r--r-- | include/linux/cgroup-defs.h | 26 | ||||
| -rw-r--r-- | include/linux/cgroup.h | 13 | ||||
| -rw-r--r-- | kernel/cgroup.c | 26 |
3 files changed, 56 insertions, 9 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 10d814bcd487..df589a097539 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -84,6 +84,17 @@ enum { }; /* + * cgroup_file is the handle for a file instance created in a cgroup which + * is used, for example, to generate file changed notifications. This can + * be obtained by setting cftype->file_offset. + */ +struct cgroup_file { + /* do not access any fields from outside cgroup core */ + struct list_head node; /* anchored at css->files */ + struct kernfs_node *kn; +}; + +/* * Per-subsystem/per-cgroup state maintained by the system. This is the * fundamental structural building block that controllers deal with. * @@ -123,6 +134,9 @@ struct cgroup_subsys_state { */ u64 serial_nr; + /* all cgroup_files associated with this css */ + struct list_head files; + /* percpu_ref killing and RCU release */ struct rcu_head rcu_head; struct work_struct destroy_work; @@ -226,8 +240,8 @@ struct cgroup { int populated_cnt; struct kernfs_node *kn; /* cgroup kernfs entry */ - struct kernfs_node *procs_kn; /* kn for "cgroup.procs" */ - struct kernfs_node *events_kn; /* kn for "cgroup.events" */ + struct cgroup_file procs_file; /* handle for "cgroup.procs" */ + struct cgroup_file events_file; /* handle for "cgroup.events" */ /* * The bitmask of subsystems enabled on the child cgroups. @@ -336,6 +350,14 @@ struct cftype { unsigned int flags; /* + * If non-zero, should contain the offset from the start of css to + * a struct cgroup_file field. cgroup will record the handle of + * the created file into it. The recorded handle can be used as + * long as the containing css remains accessible. + */ + unsigned int file_offset; + + /* * Fields used for internal bookkeeping. Initialized automatically * during registration. */ diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 355bf2ed8867..fb717f2cba5b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -490,6 +490,19 @@ static inline void pr_cont_cgroup_path(struct cgroup *cgrp) pr_cont_kernfs_path(cgrp->kn); } +/** + * cgroup_file_notify - generate a file modified event for a cgroup_file + * @cfile: target cgroup_file + * + * @cfile must have been obtained by setting cftype->file_offset. + */ +static inline void cgroup_file_notify(struct cgroup_file *cfile) +{ + /* might not have been created due to one of the CFTYPE selector flags */ + if (cfile->kn) + kernfs_notify(cfile->kn); +} + #else /* !CONFIG_CGROUPS */ struct cgroup_subsys_state; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 06c9d1aeea9d..0be276ffe08a 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -612,8 +612,8 @@ static void cgroup_update_populated(struct cgroup *cgrp, bool populated) if (!trigger) break; - if (cgrp->events_kn) - kernfs_notify(cgrp->events_kn); + cgroup_file_notify(&cgrp->events_file); + cgrp = cgroup_parent(cgrp); } while (cgrp); } @@ -1771,6 +1771,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) INIT_LIST_HEAD(&cgrp->self.sibling); INIT_LIST_HEAD(&cgrp->self.children); + INIT_LIST_HEAD(&cgrp->self.files); INIT_LIST_HEAD(&cgrp->cset_links); INIT_LIST_HEAD(&cgrp->pidlists); mutex_init(&cgrp->pidlist_mutex); @@ -2562,7 +2563,7 @@ static int cgroup_procs_write_permission(struct task_struct *task, cgrp = cgroup_parent(cgrp); ret = -ENOMEM; - inode = kernfs_get_inode(sb, cgrp->procs_kn); + inode = kernfs_get_inode(sb, cgrp->procs_file.kn); if (inode) { ret = inode_permission(inode, MAY_WRITE); iput(inode); @@ -3253,10 +3254,14 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, return ret; } - if (cft->write == cgroup_procs_write) - cgrp->procs_kn = kn; - else if (cft->seq_show == cgroup_events_show) - cgrp->events_kn = kn; + if (cft->file_offset) { + struct cgroup_file *cfile = (void *)css + cft->file_offset; + + kernfs_get(kn); + cfile->kn = kn; + list_add(&cfile->node, &css->files); + } + return 0; } @@ -4408,6 +4413,7 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css, static struct cftype cgroup_dfl_base_files[] = { { .name = "cgroup.procs", + .file_offset = offsetof(struct cgroup, procs_file), .seq_start = cgroup_pidlist_start, .seq_next = cgroup_pidlist_next, .seq_stop = cgroup_pidlist_stop, @@ -4433,6 +4439,7 @@ static struct cftype cgroup_dfl_base_files[] = { { .name = "cgroup.events", .flags = CFTYPE_NOT_ON_ROOT, + .file_offset = offsetof(struct cgroup, events_file), .seq_show = cgroup_events_show, }, { } /* terminate */ @@ -4511,9 +4518,13 @@ static void css_free_work_fn(struct work_struct *work) container_of(work, struct cgroup_subsys_state, destroy_work); struct cgroup_subsys *ss = css->ss; struct cgroup *cgrp = css->cgroup; + struct cgroup_file *cfile; percpu_ref_exit(&css->refcnt); + list_for_each_entry(cfile, &css->files, node) + kernfs_put(cfile->kn); + if (ss) { /* css free path */ int id = css->id; @@ -4618,6 +4629,7 @@ static void init_and_link_css(struct cgroup_subsys_state *css, css->ss = ss; INIT_LIST_HEAD(&css->sibling); INIT_LIST_HEAD(&css->children); + INIT_LIST_HEAD(&css->files); css->serial_nr = css_serial_nr_next++; if (cgroup_parent(cgrp)) { |