diff options
| -rw-r--r-- | kernel/cgroup.c | 147 |
1 files changed, 71 insertions, 76 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 3409698bd9fd..cef688128fb8 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -259,6 +259,31 @@ static int notify_on_release(const struct cgroup *cgrp) return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); } +/** + * for_each_subsys - iterate all loaded cgroup subsystems + * @ss: the iteration cursor + * @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end + * + * Should be called under cgroup_mutex. + */ +#define for_each_subsys(ss, i) \ + for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \ + if (({ lockdep_assert_held(&cgroup_mutex); \ + !((ss) = cgroup_subsys[i]); })) { } \ + else + +/** + * for_each_builtin_subsys - iterate all built-in cgroup subsystems + * @ss: the iteration cursor + * @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end + * + * Bulit-in subsystems are always present and iteration itself doesn't + * require any synchronization. + */ +#define for_each_builtin_subsys(ss, i) \ + for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \ + (((ss) = cgroup_subsys[i]) || true); (i)++) + /* iterate each subsystem attached to a hierarchy */ #define for_each_root_subsys(root, ss) \ list_for_each_entry((ss), &(root)->subsys_list, sibling) @@ -356,10 +381,11 @@ static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) { - int i; unsigned long key = 0UL; + struct cgroup_subsys *ss; + int i; - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) + for_each_subsys(ss, i) key += (unsigned long)css[i]; key = (key >> 16) ^ key; @@ -514,6 +540,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset, struct cgroup_subsys_state *template[]) { struct cgroupfs_root *root = cgrp->root; + struct cgroup_subsys *ss; struct css_set *cset; unsigned long key; int i; @@ -523,7 +550,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset, * new css_set. while subsystems can change globally, the entries here * won't change, so no need for locking. */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + for_each_subsys(ss, i) { if (root->subsys_mask & (1UL << i)) { /* Subsystem is in this hierarchy. So we want * the subsystem state from the new @@ -982,23 +1009,19 @@ static int rebind_subsystems(struct cgroupfs_root *root, unsigned long added_mask, unsigned removed_mask) { struct cgroup *cgrp = &root->top_cgroup; + struct cgroup_subsys *ss; int i; BUG_ON(!mutex_is_locked(&cgroup_mutex)); BUG_ON(!mutex_is_locked(&cgroup_root_mutex)); /* Check that any added subsystems are currently free */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { + for_each_subsys(ss, i) { unsigned long bit = 1UL << i; - struct cgroup_subsys *ss = cgroup_subsys[i]; + if (!(bit & added_mask)) continue; - /* - * Nobody should tell us to do a subsys that doesn't exist: - * parse_cgroupfs_options should catch that case and refcounts - * ensure that subsystems won't disappear once selected. - */ - BUG_ON(ss == NULL); + if (ss->root != &cgroup_dummy_root) { /* Subsystem isn't free */ return -EBUSY; @@ -1013,12 +1036,11 @@ static int rebind_subsystems(struct cgroupfs_root *root, return -EBUSY; /* Process each subsystem */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; + for_each_subsys(ss, i) { unsigned long bit = 1UL << i; + if (bit & added_mask) { /* We're binding this subsystem to this hierarchy */ - BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i]); BUG_ON(!cgroup_dummy_top->subsys[i]); BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top); @@ -1034,7 +1056,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, root->subsys_mask |= bit; } else if (bit & removed_mask) { /* We're removing this subsystem */ - BUG_ON(ss == NULL); BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]); BUG_ON(cgrp->subsys[i]->cgroup != cgrp); @@ -1050,7 +1071,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, root->subsys_mask &= ~bit; } else if (bit & root->subsys_mask) { /* Subsystem state should already exist */ - BUG_ON(ss == NULL); BUG_ON(!cgrp->subsys[i]); /* * a refcount was taken, but we already had one, so @@ -1117,8 +1137,9 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) char *token, *o = data; bool all_ss = false, one_ss = false; unsigned long mask = (unsigned long)-1; - int i; bool module_pin_failed = false; + struct cgroup_subsys *ss; + int i; BUG_ON(!mutex_is_locked(&cgroup_mutex)); @@ -1195,10 +1216,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) continue; } - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - if (ss == NULL) - continue; + for_each_subsys(ss, i) { if (strcmp(token, ss->name)) continue; if (ss->disabled) @@ -1221,16 +1239,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) * otherwise if 'none', 'name=' and a subsystem name options * were not specified, let's default to 'all' */ - if (all_ss || (!one_ss && !opts->none && !opts->name)) { - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - if (ss == NULL) - continue; - if (ss->disabled) - continue; - set_bit(i, &opts->subsys_mask); - } - } + if (all_ss || (!one_ss && !opts->none && !opts->name)) + for_each_subsys(ss, i) + if (!ss->disabled) + set_bit(i, &opts->subsys_mask); /* Consistency checks */ @@ -1274,10 +1286,8 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) * take duplicate reference counts on a subsystem that's already used, * but rebind_subsystems handles this case. */ - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - unsigned long bit = 1UL << i; - - if (!(bit & opts->subsys_mask)) + for_each_subsys(ss, i) { + if (!(opts->subsys_mask & (1UL << i))) continue; if (!try_module_get(cgroup_subsys[i]->module)) { module_pin_failed = true; @@ -1306,11 +1316,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) static void drop_parsed_module_refcounts(unsigned long subsys_mask) { + struct cgroup_subsys *ss; int i; - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - unsigned long bit = 1UL << i; - if (!(bit & subsys_mask)) + for_each_subsys(ss, i) { + if (!(subsys_mask & (1UL << i))) continue; module_put(cgroup_subsys[i]->module); } @@ -4822,7 +4832,9 @@ EXPORT_SYMBOL_GPL(cgroup_unload_subsys); */ int __init cgroup_init_early(void) { + struct cgroup_subsys *ss; int i; + atomic_set(&init_css_set.refcount, 1); INIT_LIST_HEAD(&init_css_set.cgrp_links); INIT_LIST_HEAD(&init_css_set.tasks); @@ -4837,13 +4849,8 @@ int __init cgroup_init_early(void) list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links); list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links); - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - - /* at bootup time, we don't worry about modular subsystems */ - if (!ss || ss->module) - continue; - + /* at bootup time, we don't worry about modular subsystems */ + for_each_builtin_subsys(ss, i) { BUG_ON(!ss->name); BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN); BUG_ON(!ss->css_alloc); @@ -4868,20 +4875,15 @@ int __init cgroup_init_early(void) */ int __init cgroup_init(void) { - int err; - int i; + struct cgroup_subsys *ss; unsigned long key; + int i, err; err = bdi_init(&cgroup_backing_dev_info); if (err) return err; - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - - /* at bootup time, we don't worry about modular subsystems */ - if (!ss || ss->module) - continue; + for_each_builtin_subsys(ss, i) { if (!ss->early_init) cgroup_init_subsys(ss); if (ss->use_id) @@ -4990,6 +4992,7 @@ out: /* Display information about each subsystem and each hierarchy */ static int proc_cgroupstats_show(struct seq_file *m, void *v) { + struct cgroup_subsys *ss; int i; seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); @@ -4999,14 +5002,12 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v) * subsys/hierarchy state. */ mutex_lock(&cgroup_mutex); - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - if (ss == NULL) - continue; + + for_each_subsys(ss, i) 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); return 0; } @@ -5060,6 +5061,7 @@ void cgroup_fork(struct task_struct *child) */ void cgroup_post_fork(struct task_struct *child) { + struct cgroup_subsys *ss; int i; /* @@ -5096,12 +5098,9 @@ void cgroup_post_fork(struct task_struct *child) * of the array can be freed at module unload, so we * can't touch that. */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - + for_each_builtin_subsys(ss, i) if (ss->fork) ss->fork(child); - } } } @@ -5142,6 +5141,7 @@ void cgroup_post_fork(struct task_struct *child) */ void cgroup_exit(struct task_struct *tsk, int run_callbacks) { + struct cgroup_subsys *ss; struct css_set *cset; int i; @@ -5167,13 +5167,12 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks) * fork/exit callbacks are supported only for builtin * subsystems, see cgroup_post_fork() for details. */ - for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - + for_each_builtin_subsys(ss, i) { if (ss->exit) { struct cgroup *old_cgrp = rcu_dereference_raw(cset->subsys[i])->cgroup; struct cgroup *cgrp = task_cgroup(tsk, i); + ss->exit(cgrp, old_cgrp, tsk); } } @@ -5280,23 +5279,19 @@ static void cgroup_release_agent(struct work_struct *work) static int __init cgroup_disable(char *str) { - int i; + struct cgroup_subsys *ss; char *token; + int i; while ((token = strsep(&str, ",")) != NULL) { if (!*token) continue; - for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { - struct cgroup_subsys *ss = cgroup_subsys[i]; - - /* - * cgroup_disable, being at boot time, can't - * know about module subsystems, so we don't - * worry about them. - */ - if (!ss || ss->module) - continue; + /* + * cgroup_disable, being at boot time, can't know about + * module subsystems, so we don't worry about them. + */ + for_each_builtin_subsys(ss, i) { if (!strcmp(token, ss->name)) { ss->disabled = 1; printk(KERN_INFO "Disabling %s control group" |