From: Tejun Heo Subject: [PATCH cgroup/for-4.17 1/2] cgroup: Explicitly remove core interface files Date: Fri, 23 Mar 2018 12:47:22 -0700 Message-ID: <20180323194722.GE2149215@devbig577.frc2.facebook.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:mime-version :content-disposition:user-agent; bh=bplhk+i4mlhtBowJXHAdpxdbwJuRMZ2/B3b8WkTl6dI=; b=ih9zV4g7gUIvBkc8K6pPSJpFs75z/Am3cnGwkBJ4K/cokjZcBotXevtrHAhKRKLRYg axfKdHt/B3x7ZUgdHd2ceMb/YCvg8s9LwH5qEVygDEDcBUdrkLRS/pFa+vVsf1l6VeEj RC8pzWLmz89PZg4rpKLnE7WTZP0wOqkRSCJlBqwApyY6pUmGgzvytCcfyKiFvH+6v8L+ /whu4erozy8EehBnZ8XRKEDj4DRYZmLWTFURqpIFUmXdtfGoCWJFvuXtRO+pH8AfZfre TQ7nC7I+XydlwOE3eJKmnhUQgSpYhgQDFPaEWY6EzQy1Cmhq/dr+kf1Z1p8WhGRKCuG0 ocWA== Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Li Zefan , Johannes Weiner Cc: cgroups@vger.kernel.org, kernel-team@fb.com, linux-kernel@vger.kernel.org The "cgroup." core interface files bypass the usual interface removal path and get removed recursively along with the cgroup itself. While this works now, the subtle discrepancy gets in the way of implementing common mechanisms. This patch updates cgroup core interface file handling so that it's consistent with controller interface files. When added, the css is marked CSS_VISIBLE and they're explicitly removed before the cgroup is destroyed. This doesn't cause user-visible behavior changes. Signed-off-by: Tejun Heo --- kernel/cgroup/cgroup.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-) --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1573,8 +1573,17 @@ static void css_clear_dir(struct cgroup_ css->flags &= ~CSS_VISIBLE; - list_for_each_entry(cfts, &css->ss->cfts, node) + if (!css->ss) { + if (cgroup_on_dfl(cgrp)) + cfts = cgroup_base_files; + else + cfts = cgroup1_base_files; + cgroup_addrm_files(css, cgrp, cfts, false); + } else { + list_for_each_entry(cfts, &css->ss->cfts, node) + cgroup_addrm_files(css, cgrp, cfts, false); + } } /** @@ -1598,14 +1607,16 @@ static int css_populate_dir(struct cgrou else cfts = cgroup1_base_files; - return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); - } - - 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; + ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); + if (ret < 0) + return ret; + } else { + 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; + } } } @@ -5097,10 +5108,8 @@ static int cgroup_destroy_locked(struct for_each_css(css, ssid, cgrp) kill_css(css); - /* - * Remove @cgrp directory along with the base files. @cgrp has an - * extra ref on its kn. - */ + /* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */ + css_clear_dir(&cgrp->self); kernfs_remove(cgrp->kn); if (parent && cgroup_is_threaded(cgrp))