From b85d20404cef6493f9d2edbafe83f9c72aece9a8 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 6 Dec 2013 15:11:57 -0500 Subject: [PATCH] cgroup: remove for_each_root_subsys() After the previous patch which introduced for_each_css(), for_each_root_subsys() only has two users left. This patch replaces it with for_each_subsys() + explicit subsys_mask testing and remove for_each_root_subsys() along with cgroupfs_root->subsys_list handling. This patch doesn't introduce any behavior changes. Signed-off-by: Tejun Heo Acked-by: Li Zefan --- include/linux/cgroup.h | 9 +-------- kernel/cgroup.c | 37 +++++++++++++++---------------------- 2 files changed, 16 insertions(+), 30 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8b9a594..cfaf416 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -319,9 +319,6 @@ struct cgroupfs_root { /* Unique id for this hierarchy. */ int hierarchy_id; - /* A list running through the attached subsystems */ - struct list_head subsys_list; - /* The root cgroup for this hierarchy */ struct cgroup top_cgroup; @@ -617,12 +614,8 @@ struct cgroup_subsys { #define MAX_CGROUP_TYPE_NAMELEN 32 const char *name; - /* - * Link to parent, and list entry in parent's children. - * Protected by cgroup_lock() - */ + /* link to parent, protected by cgroup_lock() */ struct cgroupfs_root *root; - struct list_head sibling; /* list of cftype_sets */ struct list_head cftsets; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 329fde8..fb1193b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -283,10 +283,6 @@ static int notify_on_release(const struct cgroup *cgrp) 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) - /* iterate across the active hierarchies */ #define for_each_active_root(root) \ list_for_each_entry((root), &cgroup_roots, root_list) @@ -1033,7 +1029,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, cgroup_css(cgroup_dummy_top, ss)); cgroup_css(cgrp, ss)->cgroup = cgrp; - list_move(&ss->sibling, &root->subsys_list); ss->root = root; if (ss->bind) ss->bind(cgroup_css(cgrp, ss)); @@ -1052,7 +1047,6 @@ static int rebind_subsystems(struct cgroupfs_root *root, RCU_INIT_POINTER(cgrp->subsys[i], NULL); cgroup_subsys[i]->root = &cgroup_dummy_root; - list_move(&ss->sibling, &cgroup_dummy_root.subsys_list); /* subsystem is now free - drop reference on module */ module_put(ss->module); @@ -1079,10 +1073,12 @@ static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) { struct cgroupfs_root *root = dentry->d_sb->s_fs_info; struct cgroup_subsys *ss; + int ssid; mutex_lock(&cgroup_root_mutex); - for_each_root_subsys(root, ss) - seq_printf(seq, ",%s", ss->name); + for_each_subsys(ss, ssid) + if (root->subsys_mask & (1 << ssid)) + seq_printf(seq, ",%s", ss->name); if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) seq_puts(seq, ",sane_behavior"); if (root->flags & CGRP_ROOT_NOPREFIX) @@ -1352,7 +1348,6 @@ static void init_cgroup_root(struct cgroupfs_root *root) { struct cgroup *cgrp = &root->top_cgroup; - INIT_LIST_HEAD(&root->subsys_list); INIT_LIST_HEAD(&root->root_list); root->number_of_cgroups = 1; cgrp->root = root; @@ -4151,7 +4146,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, struct cgroup *cgrp; struct cgroup_name *name; struct cgroupfs_root *root = parent->root; - int err = 0; + int ssid, err = 0; struct cgroup_subsys *ss; struct super_block *sb = root->sb; @@ -4237,10 +4232,12 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, goto err_destroy; /* let's create and online css's */ - for_each_root_subsys(root, ss) { - err = create_css(cgrp, ss); - if (err) - goto err_destroy; + for_each_subsys(ss, ssid) { + if (root->subsys_mask & (1 << ssid)) { + err = create_css(cgrp, ss); + if (err) + goto err_destroy; + } } mutex_unlock(&cgroup_mutex); @@ -4536,7 +4533,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) cgroup_init_cftsets(ss); /* Create the top cgroup state for this subsystem */ - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); ss->root = &cgroup_dummy_root; css = ss->css_alloc(cgroup_css(cgroup_dummy_top, ss)); /* We don't handle early failures gracefully */ @@ -4626,7 +4622,6 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) return PTR_ERR(css); } - list_add(&ss->sibling, &cgroup_dummy_root.subsys_list); ss->root = &cgroup_dummy_root; /* our new subsystem will be attached to the dummy hierarchy. */ @@ -4702,9 +4697,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) /* deassign the subsys_id */ cgroup_subsys[ss->subsys_id] = NULL; - /* remove subsystem from the dummy root's list of subsystems */ - list_del_init(&ss->sibling); - /* * disentangle the css from all css_sets attached to the dummy * top. as in loading, we need to pay our respects to the hashtable @@ -4901,11 +4893,12 @@ int proc_cgroup_show(struct seq_file *m, void *v) for_each_active_root(root) { struct cgroup_subsys *ss; struct cgroup *cgrp; - int count = 0; + int ssid, count = 0; seq_printf(m, "%d:", root->hierarchy_id); - for_each_root_subsys(root, ss) - seq_printf(m, "%s%s", count++ ? "," : "", ss->name); + for_each_subsys(ss, ssid) + if (root->subsys_mask & (1 << ssid)) + seq_printf(m, "%s%s", count++ ? "," : "", ss->name); if (strlen(root->name)) seq_printf(m, "%sname=%s", count ? "," : "", root->name); -- 2.7.4