mirror of https://gitee.com/openkylin/linux.git
cgroup: restructure file creation / removal handling
The file creation / removal path has always been a bit icky and the planned notification update requires css during file creation. Restructure as follows. * cgroup_addrm_files() now takes both @css and @cgrp and is only called directly by other file handling functions. * cgroup_populate/clear_dir() are replaced with css_populate/clear_dir() taking @css and @cgrp_override. @cgrp_override is used only when files needs to be created on / removed from a cgroup which isn't attached to @css which happens during subsystem rebinds. Subsystem loops are moved to the callers. * cgroup_add_file() now takes both @css and @cgrp. @css isn't used yet but will be used by the planned notification update. This patch doens't cause any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
This commit is contained in:
Tejun Heo
parent
1ada48387a
commit
4df8dc9031
143
kernel/cgroup.c
143
kernel/cgroup.c
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@ -221,7 +221,8 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
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bool visible);
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static void css_release(struct percpu_ref *ref);
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static void kill_css(struct cgroup_subsys_state *css);
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static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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static int cgroup_addrm_files(struct cgroup_subsys_state *css,
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struct cgroup *cgrp, struct cftype cfts[],
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bool is_add);
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/**
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@ -1313,53 +1314,57 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
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}
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/**
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* cgroup_clear_dir - remove subsys files in a cgroup directory
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* @cgrp: target cgroup
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* @subsys_mask: mask of the subsystem ids whose files should be removed
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* css_clear_dir - remove subsys files in a cgroup directory
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* @css: taget css
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* @cgrp_override: specify if target cgroup is different from css->cgroup
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*/
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static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask)
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static void css_clear_dir(struct cgroup_subsys_state *css,
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struct cgroup *cgrp_override)
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{
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struct cgroup_subsys *ss;
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int i;
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struct cgroup *cgrp = cgrp_override ?: css->cgroup;
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struct cftype *cfts;
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for_each_subsys(ss, i) {
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struct cftype *cfts;
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if (!(subsys_mask & (1 << i)))
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continue;
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list_for_each_entry(cfts, &ss->cfts, node)
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cgroup_addrm_files(cgrp, cfts, false);
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}
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list_for_each_entry(cfts, &css->ss->cfts, node)
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cgroup_addrm_files(css, cgrp, cfts, false);
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}
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/**
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* cgroup_populate_dir - create subsys files in a cgroup directory
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* @cgrp: target cgroup
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* @subsys_mask: mask of the subsystem ids whose files should be added
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* css_populate_dir - create subsys files in a cgroup directory
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* @css: target css
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* @cgrp_overried: specify if target cgroup is different from css->cgroup
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*
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* On failure, no file is added.
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*/
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static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask)
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static int css_populate_dir(struct cgroup_subsys_state *css,
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struct cgroup *cgrp_override)
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{
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struct cgroup_subsys *ss;
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int i, ret = 0;
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struct cgroup *cgrp = cgrp_override ?: css->cgroup;
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struct cftype *cfts, *failed_cfts;
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int ret;
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/* process cftsets of each subsystem */
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for_each_subsys(ss, i) {
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struct cftype *cfts;
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if (!css->ss) {
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if (cgroup_on_dfl(cgrp))
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cfts = cgroup_dfl_base_files;
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else
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cfts = cgroup_legacy_base_files;
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if (!(subsys_mask & (1 << i)))
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continue;
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return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
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}
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list_for_each_entry(cfts, &ss->cfts, node) {
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ret = cgroup_addrm_files(cgrp, cfts, true);
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if (ret < 0)
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goto err;
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list_for_each_entry(cfts, &css->ss->cfts, node) {
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ret = cgroup_addrm_files(css, cgrp, cfts, true);
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if (ret < 0) {
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failed_cfts = cfts;
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goto err;
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}
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}
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return 0;
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err:
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cgroup_clear_dir(cgrp, subsys_mask);
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list_for_each_entry(cfts, &css->ss->cfts, node) {
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if (cfts == failed_cfts)
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break;
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cgroup_addrm_files(css, cgrp, cfts, false);
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}
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return ret;
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}
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@ -1388,10 +1393,13 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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if (dst_root == &cgrp_dfl_root)
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tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask;
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ret = cgroup_populate_dir(dcgrp, tmp_ss_mask);
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if (ret) {
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if (dst_root != &cgrp_dfl_root)
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return ret;
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for_each_subsys_which(ss, ssid, &tmp_ss_mask) {
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struct cgroup *scgrp = &ss->root->cgrp;
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int tssid;
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ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp);
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if (!ret)
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continue;
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/*
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* Rebinding back to the default root is not allowed to
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@ -1399,20 +1407,27 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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* be rare. Moving subsystems back and forth even more so.
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* Just warn about it and continue.
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*/
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if (cgrp_dfl_root_visible) {
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pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n",
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ret, ss_mask);
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pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
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if (dst_root == &cgrp_dfl_root) {
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if (cgrp_dfl_root_visible) {
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pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n",
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ret, ss_mask);
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pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
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}
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continue;
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}
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for_each_subsys_which(ss, tssid, &tmp_ss_mask) {
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if (tssid == ssid)
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break;
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css_clear_dir(cgroup_css(scgrp, ss), dcgrp);
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}
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return ret;
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}
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/*
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* Nothing can fail from this point on. Remove files for the
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* removed subsystems and rebind each subsystem.
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*/
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for_each_subsys_which(ss, ssid, &ss_mask)
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cgroup_clear_dir(&ss->root->cgrp, 1 << ssid);
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for_each_subsys_which(ss, ssid, &ss_mask) {
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struct cgroup_root *src_root = ss->root;
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struct cgroup *scgrp = &src_root->cgrp;
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@ -1421,6 +1436,8 @@ static int rebind_subsystems(struct cgroup_root *dst_root,
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WARN_ON(!css || cgroup_css(dcgrp, ss));
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css_clear_dir(css, NULL);
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RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
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rcu_assign_pointer(dcgrp->subsys[ssid], css);
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ss->root = dst_root;
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@ -1791,7 +1808,6 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
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{
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LIST_HEAD(tmp_links);
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struct cgroup *root_cgrp = &root->cgrp;
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struct cftype *base_files;
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struct css_set *cset;
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int i, ret;
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@ -1830,12 +1846,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask)
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}
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root_cgrp->kn = root->kf_root->kn;
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if (root == &cgrp_dfl_root)
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base_files = cgroup_dfl_base_files;
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else
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base_files = cgroup_legacy_base_files;
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ret = cgroup_addrm_files(root_cgrp, base_files, true);
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ret = css_populate_dir(&root_cgrp->self, NULL);
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if (ret)
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goto destroy_root;
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@ -2985,7 +2996,8 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
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ret = create_css(child, ss,
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cgrp->subtree_control & (1 << ssid));
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else
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ret = cgroup_populate_dir(child, 1 << ssid);
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ret = css_populate_dir(cgroup_css(child, ss),
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NULL);
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if (ret)
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goto err_undo_css;
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}
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@ -3018,7 +3030,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
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if (css_disable & (1 << ssid)) {
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kill_css(css);
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} else {
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cgroup_clear_dir(child, 1 << ssid);
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css_clear_dir(css, NULL);
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if (ss->css_reset)
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ss->css_reset(css);
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}
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@ -3066,7 +3078,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
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if (css_enable & (1 << ssid))
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kill_css(css);
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else
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cgroup_clear_dir(child, 1 << ssid);
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css_clear_dir(css, NULL);
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}
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}
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goto out_unlock;
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@ -3218,7 +3230,8 @@ static int cgroup_kn_set_ugid(struct kernfs_node *kn)
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return kernfs_setattr(kn, &iattr);
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}
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static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
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static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
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struct cftype *cft)
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{
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char name[CGROUP_FILE_NAME_MAX];
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struct kernfs_node *kn;
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@ -3249,14 +3262,16 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft)
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/**
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* cgroup_addrm_files - add or remove files to a cgroup directory
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* @cgrp: the target cgroup
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* @css: the target css
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* @cgrp: the target cgroup (usually css->cgroup)
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* @cfts: array of cftypes to be added
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* @is_add: whether to add or remove
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*
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* Depending on @is_add, add or remove files defined by @cfts on @cgrp.
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* For removals, this function never fails.
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*/
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static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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static int cgroup_addrm_files(struct cgroup_subsys_state *css,
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struct cgroup *cgrp, struct cftype cfts[],
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bool is_add)
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{
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struct cftype *cft, *cft_end = NULL;
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@ -3277,7 +3292,7 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
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continue;
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if (is_add) {
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ret = cgroup_add_file(cgrp, cft);
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ret = cgroup_add_file(css, cgrp, cft);
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if (ret) {
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pr_warn("%s: failed to add %s, err=%d\n",
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__func__, cft->name, ret);
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@ -3309,7 +3324,7 @@ static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
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if (cgroup_is_dead(cgrp))
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continue;
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ret = cgroup_addrm_files(cgrp, cfts, is_add);
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ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
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if (ret)
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break;
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}
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@ -4685,7 +4700,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
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css->id = err;
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if (visible) {
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err = cgroup_populate_dir(cgrp, 1 << ss->id);
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err = css_populate_dir(css, NULL);
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if (err)
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goto err_free_id;
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}
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@ -4711,7 +4726,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss,
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err_list_del:
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list_del_rcu(&css->sibling);
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cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
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css_clear_dir(css, NULL);
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err_free_id:
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cgroup_idr_remove(&ss->css_idr, css->id);
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err_free_percpu_ref:
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@ -4728,7 +4743,6 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
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struct cgroup_root *root;
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struct cgroup_subsys *ss;
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struct kernfs_node *kn;
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struct cftype *base_files;
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int ssid, ret;
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/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
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@ -4804,12 +4818,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
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if (ret)
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goto out_destroy;
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if (cgroup_on_dfl(cgrp))
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base_files = cgroup_dfl_base_files;
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else
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base_files = cgroup_legacy_base_files;
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ret = cgroup_addrm_files(cgrp, base_files, true);
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ret = css_populate_dir(&cgrp->self, NULL);
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if (ret)
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goto out_destroy;
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@ -4896,7 +4905,7 @@ static void kill_css(struct cgroup_subsys_state *css)
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* This must happen before css is disassociated with its cgroup.
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* See seq_css() for details.
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*/
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cgroup_clear_dir(css->cgroup, 1 << css->ss->id);
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css_clear_dir(css, NULL);
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/*
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* Killing would put the base ref, but we need to keep it alive
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