cgroup_on_dfl() tests whether the cgroup's root is the default hierarchy; however, an individual controller is only interested in whether the controller is attached to the default hierarchy and never tests a cgroup which doesn't belong to the hierarchy that the controller is attached to.
This patch replaces cgroup_on_dfl() tests in controllers with faster static_key based cgroup_subsys_on_dfl(). This leaves cgroup core as the only user of cgroup_on_dfl() and the function is moved from the header file to cgroup.c. Signed-off-by: Tejun Heo <t...@kernel.org> Cc: Vivek Goyal <vgo...@redhat.com> Cc: Jens Axboe <ax...@kernel.dk> Cc: Li Zefan <lize...@huawei.com> Cc: Johannes Weiner <han...@cmpxchg.org> Cc: Michal Hocko <mho...@kernel.org> --- block/blk-throttle.c | 2 +- block/cfq-iosched.c | 4 ++-- include/linux/cgroup.h | 58 -------------------------------------------------- kernel/cgroup.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ kernel/cpuset.c | 23 +++++++++++--------- mm/memcontrol.c | 4 ++-- 6 files changed, 76 insertions(+), 73 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index c75a263..2149a1d 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -369,7 +369,7 @@ static void throtl_pd_init(struct blkg_policy_data *pd) * regardless of the position of the group in the hierarchy. */ sq->parent_sq = &td->service_queue; - if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent) + if (cgroup_subsys_on_dfl(io_cgrp_subsys) && blkg->parent) sq->parent_sq = &blkg_to_tg(blkg->parent)->service_queue; tg->td = td; } diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 04de884..1f9093e 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1581,7 +1581,7 @@ static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp) static void cfq_cpd_init(struct blkcg_policy_data *cpd) { struct cfq_group_data *cgd = cpd_to_cfqgd(cpd); - unsigned int weight = cgroup_on_dfl(blkcg_root.css.cgroup) ? + unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL; if (cpd_to_blkcg(cpd) == &blkcg_root) @@ -1599,7 +1599,7 @@ static void cfq_cpd_free(struct blkcg_policy_data *cpd) static void cfq_cpd_bind(struct blkcg_policy_data *cpd) { struct blkcg *blkcg = cpd_to_blkcg(cpd); - bool on_dfl = cgroup_on_dfl(blkcg_root.css.cgroup); + bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys); unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL; if (blkcg == &blkcg_root) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index c3a9f1e..355bf2e 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -433,64 +433,6 @@ static inline struct cgroup *task_cgroup(struct task_struct *task, return task_css(task, subsys_id)->cgroup; } -/** - * cgroup_on_dfl - test whether a cgroup is on the default hierarchy - * @cgrp: the cgroup of interest - * - * The default hierarchy is the v2 interface of cgroup and this function - * can be used to test whether a cgroup is on the default hierarchy for - * cases where a subsystem should behave differnetly depending on the - * interface version. - * - * The set of behaviors which change on the default hierarchy are still - * being determined and the mount option is prefixed with __DEVEL__. - * - * List of changed behaviors: - * - * - Mount options "noprefix", "xattr", "clone_children", "release_agent" - * and "name" are disallowed. - * - * - When mounting an existing superblock, mount options should match. - * - * - Remount is disallowed. - * - * - rename(2) is disallowed. - * - * - "tasks" is removed. Everything should be at process granularity. Use - * "cgroup.procs" instead. - * - * - "cgroup.procs" is not sorted. pids will be unique unless they got - * recycled inbetween reads. - * - * - "release_agent" and "notify_on_release" are removed. Replacement - * notification mechanism will be implemented. - * - * - "cgroup.clone_children" is removed. - * - * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup - * and its descendants contain no task; otherwise, 1. The file also - * generates kernfs notification which can be monitored through poll and - * [di]notify when the value of the file changes. - * - * - cpuset: tasks will be kept in empty cpusets when hotplug happens and - * take masks of ancestors with non-empty cpus/mems, instead of being - * moved to an ancestor. - * - * - cpuset: a task can be moved into an empty cpuset, and again it takes - * masks of ancestors. - * - * - memcg: use_hierarchy is on by default and the cgroup file for the flag - * is not created. - * - * - blkcg: blk-throttle becomes properly hierarchical. - * - * - debug: disallowed on the default hierarchy. - */ -static inline bool cgroup_on_dfl(const struct cgroup *cgrp) -{ - return cgrp->root == &cgrp_dfl_root; -} - /* no synchronization, the result can only be used as a hint */ static inline bool cgroup_has_tasks(struct cgroup *cgrp) { diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 5703ba7..c24f929 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -237,6 +237,64 @@ static bool cgroup_ssid_enabled(int ssid) return static_key_enabled(cgroup_subsys_enabled_key[ssid]); } +/** + * cgroup_on_dfl - test whether a cgroup is on the default hierarchy + * @cgrp: the cgroup of interest + * + * The default hierarchy is the v2 interface of cgroup and this function + * can be used to test whether a cgroup is on the default hierarchy for + * cases where a subsystem should behave differnetly depending on the + * interface version. + * + * The set of behaviors which change on the default hierarchy are still + * being determined and the mount option is prefixed with __DEVEL__. + * + * List of changed behaviors: + * + * - Mount options "noprefix", "xattr", "clone_children", "release_agent" + * and "name" are disallowed. + * + * - When mounting an existing superblock, mount options should match. + * + * - Remount is disallowed. + * + * - rename(2) is disallowed. + * + * - "tasks" is removed. Everything should be at process granularity. Use + * "cgroup.procs" instead. + * + * - "cgroup.procs" is not sorted. pids will be unique unless they got + * recycled inbetween reads. + * + * - "release_agent" and "notify_on_release" are removed. Replacement + * notification mechanism will be implemented. + * + * - "cgroup.clone_children" is removed. + * + * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup + * and its descendants contain no task; otherwise, 1. The file also + * generates kernfs notification which can be monitored through poll and + * [di]notify when the value of the file changes. + * + * - cpuset: tasks will be kept in empty cpusets when hotplug happens and + * take masks of ancestors with non-empty cpus/mems, instead of being + * moved to an ancestor. + * + * - cpuset: a task can be moved into an empty cpuset, and again it takes + * masks of ancestors. + * + * - memcg: use_hierarchy is on by default and the cgroup file for the flag + * is not created. + * + * - blkcg: blk-throttle becomes properly hierarchical. + * + * - debug: disallowed on the default hierarchy. + */ +static bool cgroup_on_dfl(const struct cgroup *cgrp) +{ + return cgrp->root == &cgrp_dfl_root; +} + /* IDR wrappers which synchronize using cgroup_idr_lock */ static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index f0acff0..20eedd8 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -473,7 +473,8 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) /* On legacy hiearchy, we must be a subset of our parent cpuset. */ ret = -EACCES; - if (!cgroup_on_dfl(cur->css.cgroup) && !is_cpuset_subset(trial, par)) + if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && + !is_cpuset_subset(trial, par)) goto out; /* @@ -879,7 +880,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus) * If it becomes empty, inherit the effective mask of the * parent, which is guaranteed to have some CPUs. */ - if (cgroup_on_dfl(cp->css.cgroup) && cpumask_empty(new_cpus)) + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && + cpumask_empty(new_cpus)) cpumask_copy(new_cpus, parent->effective_cpus); /* Skip the whole subtree if the cpumask remains the same. */ @@ -896,7 +898,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus) cpumask_copy(cp->effective_cpus, new_cpus); spin_unlock_irq(&callback_lock); - WARN_ON(!cgroup_on_dfl(cp->css.cgroup) && + WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && !cpumask_equal(cp->cpus_allowed, cp->effective_cpus)); update_tasks_cpumask(cp); @@ -1135,7 +1137,8 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) * If it becomes empty, inherit the effective mask of the * parent, which is guaranteed to have some MEMs. */ - if (cgroup_on_dfl(cp->css.cgroup) && nodes_empty(*new_mems)) + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && + nodes_empty(*new_mems)) *new_mems = parent->effective_mems; /* Skip the whole subtree if the nodemask remains the same. */ @@ -1152,7 +1155,7 @@ static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) cp->effective_mems = *new_mems; spin_unlock_irq(&callback_lock); - WARN_ON(!cgroup_on_dfl(cp->css.cgroup) && + WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && !nodes_equal(cp->mems_allowed, cp->effective_mems)); update_tasks_nodemask(cp); @@ -1440,7 +1443,7 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css, /* allow moving tasks into an empty cpuset if on default hierarchy */ ret = -ENOSPC; - if (!cgroup_on_dfl(css->cgroup) && + if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) goto out_unlock; @@ -1952,7 +1955,7 @@ static int cpuset_css_online(struct cgroup_subsys_state *css) cpuset_inc(); spin_lock_irq(&callback_lock); - if (cgroup_on_dfl(cs->css.cgroup)) { + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { cpumask_copy(cs->effective_cpus, parent->effective_cpus); cs->effective_mems = parent->effective_mems; } @@ -2029,7 +2032,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css) mutex_lock(&cpuset_mutex); spin_lock_irq(&callback_lock); - if (cgroup_on_dfl(root_css->cgroup)) { + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask); top_cpuset.mems_allowed = node_possible_map; } else { @@ -2210,7 +2213,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs) cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus); mems_updated = !nodes_equal(new_mems, cs->effective_mems); - if (cgroup_on_dfl(cs->css.cgroup)) + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) hotplug_update_tasks(cs, &new_cpus, &new_mems, cpus_updated, mems_updated); else @@ -2241,7 +2244,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work) static cpumask_t new_cpus; static nodemask_t new_mems; bool cpus_updated, mems_updated; - bool on_dfl = cgroup_on_dfl(top_cpuset.css.cgroup); + bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys); mutex_lock(&cpuset_mutex); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6ddaeba..b35c4cc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -434,7 +434,7 @@ struct cgroup_subsys_state *mem_cgroup_css_from_page(struct page *page) memcg = page->mem_cgroup; - if (!memcg || !cgroup_on_dfl(memcg->css.cgroup)) + if (!memcg || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) memcg = root_mem_cgroup; rcu_read_unlock(); @@ -5059,7 +5059,7 @@ static void mem_cgroup_bind(struct cgroup_subsys_state *root_css) * guarantees that @root doesn't have any children, so turning it * on for the root memcg is enough. */ - if (cgroup_on_dfl(root_css->cgroup)) + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) root_mem_cgroup->use_hierarchy = true; else root_mem_cgroup->use_hierarchy = false; -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/