Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932141AbbHKR6e (ORCPT ); Tue, 11 Aug 2015 13:58:34 -0400 Received: from mail-yk0-f178.google.com ([209.85.160.178]:33782 "EHLO mail-yk0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750975AbbHKR6b (ORCPT ); Tue, 11 Aug 2015 13:58:31 -0400 From: Tejun Heo To: hannes@cmpxchg.org, lizefan@huawei.com Cc: mhocko@kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 6/8] cgroup: restructure file creation / removal handling Date: Tue, 11 Aug 2015 13:58:07 -0400 Message-Id: <1439315889-3492-7-git-send-email-tj@kernel.org> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1439315889-3492-1-git-send-email-tj@kernel.org> References: <1439315889-3492-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11265 Lines: 343 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 Cc: Li Zefan Cc: Johannes Weiner --- kernel/cgroup.c | 143 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 76 insertions(+), 67 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 67d2ba3..b287522 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -200,7 +200,8 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, bool visible); static void css_release(struct percpu_ref *ref); static void kill_css(struct cgroup_subsys_state *css); -static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], +static int cgroup_addrm_files(struct cgroup_subsys_state *css, + struct cgroup *cgrp, struct cftype cfts[], bool is_add); /* IDR wrappers which synchronize using cgroup_idr_lock */ @@ -1218,53 +1219,57 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) } /** - * cgroup_clear_dir - remove subsys files in a cgroup directory - * @cgrp: target cgroup - * @subsys_mask: mask of the subsystem ids whose files should be removed + * css_clear_dir - remove subsys files in a cgroup directory + * @css: taget css + * @cgrp_override: specify if target cgroup is different from css->cgroup */ -static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) +static void css_clear_dir(struct cgroup_subsys_state *css, + struct cgroup *cgrp_override) { - struct cgroup_subsys *ss; - int i; + struct cgroup *cgrp = cgrp_override ?: css->cgroup; + struct cftype *cfts; - for_each_subsys(ss, i) { - struct cftype *cfts; - - if (!(subsys_mask & (1 << i))) - continue; - list_for_each_entry(cfts, &ss->cfts, node) - cgroup_addrm_files(cgrp, cfts, false); - } + list_for_each_entry(cfts, &css->ss->cfts, node) + cgroup_addrm_files(css, cgrp, cfts, false); } /** - * cgroup_populate_dir - create subsys files in a cgroup directory - * @cgrp: target cgroup - * @subsys_mask: mask of the subsystem ids whose files should be added + * css_populate_dir - create subsys files in a cgroup directory + * @css: target css + * @cgrp_overried: specify if target cgroup is different from css->cgroup * * On failure, no file is added. */ -static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask) +static int css_populate_dir(struct cgroup_subsys_state *css, + struct cgroup *cgrp_override) { - struct cgroup_subsys *ss; - int i, ret = 0; + struct cgroup *cgrp = cgrp_override ?: css->cgroup; + struct cftype *cfts, *failed_cfts; + int ret; - /* process cftsets of each subsystem */ - for_each_subsys(ss, i) { - struct cftype *cfts; + if (!css->ss) { + if (cgroup_on_dfl(cgrp)) + cfts = cgroup_dfl_base_files; + else + cfts = cgroup_legacy_base_files; - if (!(subsys_mask & (1 << i))) - continue; + return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); + } - list_for_each_entry(cfts, &ss->cfts, node) { - ret = cgroup_addrm_files(cgrp, cfts, true); - if (ret < 0) - goto err; + list_for_each_entry(cfts, &css->ss->cfts, node) { + ret = cgroup_addrm_files(css, cgrp, cfts, true); + if (ret < 0) { + failed_cfts = cfts; + goto err; } } return 0; err: - cgroup_clear_dir(cgrp, subsys_mask); + list_for_each_entry(cfts, &css->ss->cfts, node) { + if (cfts == failed_cfts) + break; + cgroup_addrm_files(css, cgrp, cfts, false); + } return ret; } @@ -1293,10 +1298,13 @@ static int rebind_subsystems(struct cgroup_root *dst_root, if (dst_root == &cgrp_dfl_root) tmp_ss_mask &= ~cgrp_dfl_root_inhibit_ss_mask; - ret = cgroup_populate_dir(dcgrp, tmp_ss_mask); - if (ret) { - if (dst_root != &cgrp_dfl_root) - return ret; + for_each_subsys_which(ss, ssid, &tmp_ss_mask) { + struct cgroup *scgrp = &ss->root->cgrp; + int tssid; + + ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp); + if (!ret) + continue; /* * Rebinding back to the default root is not allowed to @@ -1304,20 +1312,27 @@ static int rebind_subsystems(struct cgroup_root *dst_root, * be rare. Moving subsystems back and forth even more so. * Just warn about it and continue. */ - if (cgrp_dfl_root_visible) { - pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", - ret, ss_mask); - pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); + if (dst_root == &cgrp_dfl_root) { + if (cgrp_dfl_root_visible) { + pr_warn("failed to create files (%d) while rebinding 0x%lx to default root\n", + ret, ss_mask); + pr_warn("you may retry by moving them to a different hierarchy and unbinding\n"); + } + continue; } + + for_each_subsys_which(ss, tssid, &tmp_ss_mask) { + if (tssid == ssid) + break; + css_clear_dir(cgroup_css(scgrp, ss), dcgrp); + } + return ret; } /* * Nothing can fail from this point on. Remove files for the * removed subsystems and rebind each subsystem. */ - for_each_subsys_which(ss, ssid, &ss_mask) - cgroup_clear_dir(&ss->root->cgrp, 1 << ssid); - for_each_subsys_which(ss, ssid, &ss_mask) { struct cgroup_root *src_root = ss->root; struct cgroup *scgrp = &src_root->cgrp; @@ -1326,6 +1341,8 @@ static int rebind_subsystems(struct cgroup_root *dst_root, WARN_ON(!css || cgroup_css(dcgrp, ss)); + css_clear_dir(css, NULL); + RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); rcu_assign_pointer(dcgrp->subsys[ssid], css); ss->root = dst_root; @@ -1691,7 +1708,6 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) { LIST_HEAD(tmp_links); struct cgroup *root_cgrp = &root->cgrp; - struct cftype *base_files; struct css_set *cset; int i, ret; @@ -1730,12 +1746,7 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned long ss_mask) } root_cgrp->kn = root->kf_root->kn; - if (root == &cgrp_dfl_root) - base_files = cgroup_dfl_base_files; - else - base_files = cgroup_legacy_base_files; - - ret = cgroup_addrm_files(root_cgrp, base_files, true); + ret = css_populate_dir(&root_cgrp->self, NULL); if (ret) goto destroy_root; @@ -2884,7 +2895,8 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, ret = create_css(child, ss, cgrp->subtree_control & (1 << ssid)); else - ret = cgroup_populate_dir(child, 1 << ssid); + ret = css_populate_dir(cgroup_css(child, ss), + NULL); if (ret) goto err_undo_css; } @@ -2917,7 +2929,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, if (css_disable & (1 << ssid)) { kill_css(css); } else { - cgroup_clear_dir(child, 1 << ssid); + css_clear_dir(css, NULL); if (ss->css_reset) ss->css_reset(css); } @@ -2965,7 +2977,7 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, if (css_enable & (1 << ssid)) kill_css(css); else - cgroup_clear_dir(child, 1 << ssid); + css_clear_dir(css, NULL); } } goto out_unlock; @@ -3117,7 +3129,8 @@ static int cgroup_kn_set_ugid(struct kernfs_node *kn) return kernfs_setattr(kn, &iattr); } -static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) +static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, + struct cftype *cft) { char name[CGROUP_FILE_NAME_MAX]; struct kernfs_node *kn; @@ -3148,14 +3161,16 @@ static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) /** * cgroup_addrm_files - add or remove files to a cgroup directory - * @cgrp: the target cgroup + * @css: the target css + * @cgrp: the target cgroup (usually css->cgroup) * @cfts: array of cftypes to be added * @is_add: whether to add or remove * * Depending on @is_add, add or remove files defined by @cfts on @cgrp. * For removals, this function never fails. */ -static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], +static int cgroup_addrm_files(struct cgroup_subsys_state *css, + struct cgroup *cgrp, struct cftype cfts[], bool is_add) { struct cftype *cft, *cft_end = NULL; @@ -3176,7 +3191,7 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], continue; if (is_add) { - ret = cgroup_add_file(cgrp, cft); + ret = cgroup_add_file(css, cgrp, cft); if (ret) { pr_warn("%s: failed to add %s, err=%d\n", __func__, cft->name, ret); @@ -3208,7 +3223,7 @@ static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) if (cgroup_is_dead(cgrp)) continue; - ret = cgroup_addrm_files(cgrp, cfts, is_add); + ret = cgroup_addrm_files(css, cgrp, cfts, is_add); if (ret) break; } @@ -4584,7 +4599,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, css->id = err; if (visible) { - err = cgroup_populate_dir(cgrp, 1 << ss->id); + err = css_populate_dir(css, NULL); if (err) goto err_free_id; } @@ -4610,7 +4625,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, err_list_del: list_del_rcu(&css->sibling); - cgroup_clear_dir(css->cgroup, 1 << css->ss->id); + css_clear_dir(css, NULL); err_free_id: cgroup_idr_remove(&ss->css_idr, css->id); err_free_percpu_ref: @@ -4627,7 +4642,6 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, struct cgroup_root *root; struct cgroup_subsys *ss; struct kernfs_node *kn; - struct cftype *base_files; int ssid, ret; /* Do not accept '\n' to prevent making /proc//cgroup unparsable. @@ -4703,12 +4717,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, if (ret) goto out_destroy; - if (cgroup_on_dfl(cgrp)) - base_files = cgroup_dfl_base_files; - else - base_files = cgroup_legacy_base_files; - - ret = cgroup_addrm_files(cgrp, base_files, true); + ret = css_populate_dir(&cgrp->self, NULL); if (ret) goto out_destroy; @@ -4795,7 +4804,7 @@ static void kill_css(struct cgroup_subsys_state *css) * This must happen before css is disassociated with its cgroup. * See seq_css() for details. */ - cgroup_clear_dir(css->cgroup, 1 << css->ss->id); + css_clear_dir(css, NULL); /* * Killing would put the base ref, but we need to keep it alive -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/