cgroup: implement for_each_[builtin_]subsys()
There are quite a few places where all loaded [builtin] subsys are
iterated. Implement for_each_[builtin_]subsys() and replace manual
iterations with those to simplify those places a bit. The new
iterators automatically skip NULL subsystems. This shouldn't cause
any functional difference.
Iteration loops which scan all subsystems and then skipping modular
ones explicitly are converted to use for_each_builtin_subsys().
While at it, reorder variable declarations and adjust whitespaces a
bit in the affected functions.
v2: Add lockdep_assert_held() in for_each_subsys() and add comments
about synchronization as suggested by Li.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo
Родитель
82fe9b0da0
Коммит
30159ec7a9
147
kernel/cgroup.c
147
kernel/cgroup.c
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@ -259,6 +259,31 @@ static int notify_on_release(const struct cgroup *cgrp)
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return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
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}
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/**
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* for_each_subsys - iterate all loaded cgroup subsystems
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* @ss: the iteration cursor
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* @i: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
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*
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* Should be called under cgroup_mutex.
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*/
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#define for_each_subsys(ss, i) \
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for ((i) = 0; (i) < CGROUP_SUBSYS_COUNT; (i)++) \
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if (({ lockdep_assert_held(&cgroup_mutex); \
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!((ss) = cgroup_subsys[i]); })) { } \
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else
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/**
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* for_each_builtin_subsys - iterate all built-in cgroup subsystems
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* @ss: the iteration cursor
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* @i: the index of @ss, CGROUP_BUILTIN_SUBSYS_COUNT after reaching the end
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*
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* Bulit-in subsystems are always present and iteration itself doesn't
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* require any synchronization.
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*/
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#define for_each_builtin_subsys(ss, i) \
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for ((i) = 0; (i) < CGROUP_BUILTIN_SUBSYS_COUNT && \
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(((ss) = cgroup_subsys[i]) || true); (i)++)
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/* iterate each subsystem attached to a hierarchy */
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#define for_each_root_subsys(root, ss) \
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list_for_each_entry((ss), &(root)->subsys_list, sibling)
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@ -356,10 +381,11 @@ static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
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static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
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{
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int i;
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unsigned long key = 0UL;
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struct cgroup_subsys *ss;
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int i;
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++)
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for_each_subsys(ss, i)
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key += (unsigned long)css[i];
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key = (key >> 16) ^ key;
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@ -514,6 +540,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset,
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struct cgroup_subsys_state *template[])
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{
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struct cgroupfs_root *root = cgrp->root;
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struct cgroup_subsys *ss;
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struct css_set *cset;
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unsigned long key;
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int i;
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@ -523,7 +550,7 @@ static struct css_set *find_existing_css_set(struct css_set *old_cset,
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* new css_set. while subsystems can change globally, the entries here
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* won't change, so no need for locking.
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*/
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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for_each_subsys(ss, i) {
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if (root->subsys_mask & (1UL << i)) {
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/* Subsystem is in this hierarchy. So we want
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* the subsystem state from the new
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@ -982,23 +1009,19 @@ static int rebind_subsystems(struct cgroupfs_root *root,
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unsigned long added_mask, unsigned removed_mask)
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{
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struct cgroup *cgrp = &root->top_cgroup;
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struct cgroup_subsys *ss;
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int i;
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BUG_ON(!mutex_is_locked(&cgroup_mutex));
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BUG_ON(!mutex_is_locked(&cgroup_root_mutex));
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/* Check that any added subsystems are currently free */
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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for_each_subsys(ss, i) {
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unsigned long bit = 1UL << i;
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struct cgroup_subsys *ss = cgroup_subsys[i];
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if (!(bit & added_mask))
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continue;
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/*
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* Nobody should tell us to do a subsys that doesn't exist:
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* parse_cgroupfs_options should catch that case and refcounts
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* ensure that subsystems won't disappear once selected.
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*/
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BUG_ON(ss == NULL);
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if (ss->root != &cgroup_dummy_root) {
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/* Subsystem isn't free */
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return -EBUSY;
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@ -1013,12 +1036,11 @@ static int rebind_subsystems(struct cgroupfs_root *root,
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return -EBUSY;
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/* Process each subsystem */
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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for_each_subsys(ss, i) {
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unsigned long bit = 1UL << i;
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if (bit & added_mask) {
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/* We're binding this subsystem to this hierarchy */
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BUG_ON(ss == NULL);
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BUG_ON(cgrp->subsys[i]);
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BUG_ON(!cgroup_dummy_top->subsys[i]);
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BUG_ON(cgroup_dummy_top->subsys[i]->cgroup != cgroup_dummy_top);
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@ -1034,7 +1056,6 @@ static int rebind_subsystems(struct cgroupfs_root *root,
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root->subsys_mask |= bit;
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} else if (bit & removed_mask) {
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/* We're removing this subsystem */
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BUG_ON(ss == NULL);
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BUG_ON(cgrp->subsys[i] != cgroup_dummy_top->subsys[i]);
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BUG_ON(cgrp->subsys[i]->cgroup != cgrp);
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@ -1050,7 +1071,6 @@ static int rebind_subsystems(struct cgroupfs_root *root,
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root->subsys_mask &= ~bit;
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} else if (bit & root->subsys_mask) {
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/* Subsystem state should already exist */
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BUG_ON(ss == NULL);
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BUG_ON(!cgrp->subsys[i]);
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/*
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* a refcount was taken, but we already had one, so
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@ -1117,8 +1137,9 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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char *token, *o = data;
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bool all_ss = false, one_ss = false;
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unsigned long mask = (unsigned long)-1;
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int i;
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bool module_pin_failed = false;
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struct cgroup_subsys *ss;
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int i;
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BUG_ON(!mutex_is_locked(&cgroup_mutex));
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@ -1195,10 +1216,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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continue;
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}
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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if (ss == NULL)
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continue;
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for_each_subsys(ss, i) {
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if (strcmp(token, ss->name))
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continue;
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if (ss->disabled)
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@ -1221,16 +1239,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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* otherwise if 'none', 'name=' and a subsystem name options
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* were not specified, let's default to 'all'
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*/
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if (all_ss || (!one_ss && !opts->none && !opts->name)) {
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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if (ss == NULL)
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continue;
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if (ss->disabled)
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continue;
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set_bit(i, &opts->subsys_mask);
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}
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}
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if (all_ss || (!one_ss && !opts->none && !opts->name))
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for_each_subsys(ss, i)
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if (!ss->disabled)
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set_bit(i, &opts->subsys_mask);
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/* Consistency checks */
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@ -1274,10 +1286,8 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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* take duplicate reference counts on a subsystem that's already used,
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* but rebind_subsystems handles this case.
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*/
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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unsigned long bit = 1UL << i;
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if (!(bit & opts->subsys_mask))
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for_each_subsys(ss, i) {
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if (!(opts->subsys_mask & (1UL << i)))
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continue;
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if (!try_module_get(cgroup_subsys[i]->module)) {
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module_pin_failed = true;
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@ -1306,11 +1316,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
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static void drop_parsed_module_refcounts(unsigned long subsys_mask)
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{
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struct cgroup_subsys *ss;
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int i;
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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unsigned long bit = 1UL << i;
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if (!(bit & subsys_mask))
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for_each_subsys(ss, i) {
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if (!(subsys_mask & (1UL << i)))
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continue;
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module_put(cgroup_subsys[i]->module);
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}
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@ -4822,7 +4832,9 @@ EXPORT_SYMBOL_GPL(cgroup_unload_subsys);
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*/
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int __init cgroup_init_early(void)
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{
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struct cgroup_subsys *ss;
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int i;
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atomic_set(&init_css_set.refcount, 1);
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INIT_LIST_HEAD(&init_css_set.cgrp_links);
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INIT_LIST_HEAD(&init_css_set.tasks);
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@ -4837,13 +4849,8 @@ int __init cgroup_init_early(void)
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list_add(&init_cgrp_cset_link.cset_link, &cgroup_dummy_top->cset_links);
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list_add(&init_cgrp_cset_link.cgrp_link, &init_css_set.cgrp_links);
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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/* at bootup time, we don't worry about modular subsystems */
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if (!ss || ss->module)
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continue;
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/* at bootup time, we don't worry about modular subsystems */
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for_each_builtin_subsys(ss, i) {
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BUG_ON(!ss->name);
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BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
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BUG_ON(!ss->css_alloc);
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@ -4868,20 +4875,15 @@ int __init cgroup_init_early(void)
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*/
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int __init cgroup_init(void)
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{
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int err;
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int i;
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struct cgroup_subsys *ss;
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unsigned long key;
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int i, err;
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err = bdi_init(&cgroup_backing_dev_info);
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if (err)
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return err;
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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/* at bootup time, we don't worry about modular subsystems */
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if (!ss || ss->module)
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continue;
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for_each_builtin_subsys(ss, i) {
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if (!ss->early_init)
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cgroup_init_subsys(ss);
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if (ss->use_id)
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@ -4990,6 +4992,7 @@ out:
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/* Display information about each subsystem and each hierarchy */
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static int proc_cgroupstats_show(struct seq_file *m, void *v)
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{
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struct cgroup_subsys *ss;
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int i;
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seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
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@ -4999,14 +5002,12 @@ static int proc_cgroupstats_show(struct seq_file *m, void *v)
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* subsys/hierarchy state.
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*/
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mutex_lock(&cgroup_mutex);
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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if (ss == NULL)
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continue;
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for_each_subsys(ss, i)
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seq_printf(m, "%s\t%d\t%d\t%d\n",
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ss->name, ss->root->hierarchy_id,
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ss->root->number_of_cgroups, !ss->disabled);
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}
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mutex_unlock(&cgroup_mutex);
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return 0;
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}
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@ -5060,6 +5061,7 @@ void cgroup_fork(struct task_struct *child)
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*/
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void cgroup_post_fork(struct task_struct *child)
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{
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struct cgroup_subsys *ss;
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int i;
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/*
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@ -5096,12 +5098,9 @@ void cgroup_post_fork(struct task_struct *child)
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* of the array can be freed at module unload, so we
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* can't touch that.
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*/
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for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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for_each_builtin_subsys(ss, i)
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if (ss->fork)
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ss->fork(child);
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}
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}
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}
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@ -5142,6 +5141,7 @@ void cgroup_post_fork(struct task_struct *child)
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*/
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void cgroup_exit(struct task_struct *tsk, int run_callbacks)
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{
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struct cgroup_subsys *ss;
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struct css_set *cset;
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int i;
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@ -5167,13 +5167,12 @@ void cgroup_exit(struct task_struct *tsk, int run_callbacks)
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* fork/exit callbacks are supported only for builtin
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* subsystems, see cgroup_post_fork() for details.
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*/
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for (i = 0; i < CGROUP_BUILTIN_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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for_each_builtin_subsys(ss, i) {
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if (ss->exit) {
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struct cgroup *old_cgrp =
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rcu_dereference_raw(cset->subsys[i])->cgroup;
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struct cgroup *cgrp = task_cgroup(tsk, i);
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ss->exit(cgrp, old_cgrp, tsk);
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}
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}
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@ -5280,23 +5279,19 @@ static void cgroup_release_agent(struct work_struct *work)
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static int __init cgroup_disable(char *str)
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{
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int i;
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struct cgroup_subsys *ss;
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char *token;
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int i;
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while ((token = strsep(&str, ",")) != NULL) {
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if (!*token)
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continue;
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for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
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struct cgroup_subsys *ss = cgroup_subsys[i];
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/*
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* cgroup_disable, being at boot time, can't
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* know about module subsystems, so we don't
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* worry about them.
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*/
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if (!ss || ss->module)
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continue;
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/*
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* cgroup_disable, being at boot time, can't know about
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* module subsystems, so we don't worry about them.
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*/
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for_each_builtin_subsys(ss, i) {
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if (!strcmp(token, ss->name)) {
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ss->disabled = 1;
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printk(KERN_INFO "Disabling %s control group"
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