From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 07/16] cgroup: factor out cgroup_apply_control_disable() from cgroup_subtree_control_write() Date: Wed, 24 Feb 2016 17:02:39 -0500 Message-ID: <1456351368-786-8-git-send-email-tj@kernel.org> References: <1456351368-786-1-git-send-email-tj@kernel.org> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references; bh=uIm3QqKx8Z5QKKrVPiMPVGX5TVym12J1wr/qkJHOU8E=; b=E0EtjVnN2lfPfr8yy1JCKnBDwDiDCR8U6BIYG25r7qbVgpS6KLpxNHiIJmuLsdvCCn wfvyVsJ3qw6vXcly+M1vIqN71fZX5Ev5b68UedgPcPLzW2V3uhEXBukI7WYfNnXcFX4n V/7Ct0Nbtic5+sCnmKJsYc+36NXBVu2ez8R+nE1nOt6UpmYeiw4e3rx4H+XOpKc6SapV pH9YvttVnO2DZPYng6Jl7hPvP4J6A6cONqYoAs3/qa1+obO+PPLdqjGjx904Cg2M0ydy F0z9C95stICX6o9oEkacTU60h8tcbI+fn+Msce3dUzgO/sP8pHGJZMDbq47+cbNdXGpr TS8g== In-Reply-To: <1456351368-786-1-git-send-email-tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org, Tejun Heo Factor out css disabling and hiding into cgroup_apply_control_disable(). * Nest subsystem walk inside child walk. The child walk will later be converted to subtree walk which is a bit more expensive. * Instead of operating on the differential masks @css_enable and @css_disable, simply disable or hide csses according to the current cgroup_control() and cgroup_ss_mask(). This leads to the same result and is simpler and more robust. * This allows error handling path to share the same code. Signed-off-by: Tejun Heo --- kernel/cgroup.c | 74 ++++++++++++++++++++++++++++++++------------------------- 1 file changed, 41 insertions(+), 33 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 7f1c636..4b8a6eb 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -3011,6 +3011,43 @@ static bool cgroup_drain_offline(struct cgroup *cgrp) return false; } +/** + * cgroup_apply_control_disable - kill or hide csses according to control + * @cgrp: parent of the target cgroups + * + * Walk @cgrp's children and kill and hide csses so that they match + * cgroup_ss_mask() and cgroup_visible_mask(). + * + * A css is hidden when the userland requests it to be disabled while other + * subsystems are still depending on it. The css must not actively control + * resources and be in the vanilla state if it's made visible again later. + * Controllers which may be depended upon should provide ->css_reset() for + * this purpose. + */ +static void cgroup_apply_control_disable(struct cgroup *cgrp) +{ + struct cgroup *dsct; + struct cgroup_subsys *ss; + int ssid; + + cgroup_for_each_live_child(dsct, cgrp) { + for_each_subsys(ss, ssid) { + struct cgroup_subsys_state *css = cgroup_css(dsct, ss); + + if (!css) + continue; + + if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) { + kill_css(css); + } else if (!(cgroup_control(dsct) & (1 << ss->id))) { + css_clear_dir(css, NULL); + if (ss->css_reset) + ss->css_reset(css); + } + } + } +} + /* change the enabled child controllers for a cgroup in the default hierarchy */ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, char *buf, size_t nbytes, @@ -3159,27 +3196,8 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, if (ret) goto err_undo_css; - /* - * All tasks are migrated out of disabled csses. Kill or hide - * them. A css is hidden when the userland requests it to be - * disabled while other subsystems are still depending on it. The - * css must not actively control resources and be in the vanilla - * state if it's made visible again later. Controllers which may - * be depended upon should provide ->css_reset() for this purpose. - */ - do_each_subsys_mask(ss, ssid, disable) { - cgroup_for_each_live_child(child, cgrp) { - struct cgroup_subsys_state *css = cgroup_css(child, ss); - - if (css_disable & (1 << ssid)) { - kill_css(css); - } else { - css_clear_dir(css, NULL); - if (ss->css_reset) - ss->css_reset(css); - } - } - } while_each_subsys_mask(); + /* all tasks are migrated out of disabled csses, commit disable */ + cgroup_apply_control_disable(cgrp); kernfs_activate(cgrp->kn); ret = 0; @@ -3188,22 +3206,12 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, return ret ?: nbytes; err_undo_css: + /* restore masks and shoot down new csses */ cgrp->subtree_control = old_sc; cgrp->subtree_ss_mask = old_ss; - do_each_subsys_mask(ss, ssid, enable) { - cgroup_for_each_live_child(child, cgrp) { - struct cgroup_subsys_state *css = cgroup_css(child, ss); - - if (!css) - continue; + cgroup_apply_control_disable(cgrp); - if (css_enable & (1 << ssid)) - kill_css(css); - else - css_clear_dir(css, NULL); - } - } while_each_subsys_mask(); goto out_unlock; } -- 2.5.0