From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH 13/17] cgroup: simplify cgroup_load_subsys() failure path Date: Mon, 12 Nov 2012 19:01:40 -0800 Message-ID: <1352775704-9023-14-git-send-email-tj@kernel.org> References: <1352775704-9023-1-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:x-mailer:in-reply-to :references; bh=dCiwDldr1bISU5vxemq2xvg8We1PZX5IuPfKK9G1iP8=; b=oqHf3KqKfq8sm5uUkI5OMb7nRyHSmPf85bf3Kb7B6j6PsrmXk2m63p3zj1RTaMlrDJ pcdM+xUKwdGnFsEfjCDrUCFLoBd9Wdbz4mwi+w+6KkRBt7mvv8wvE/VngQ8oTgVIsdJx 7H3PiohDQ9A4mOpGnWx11Oo/oIyUJlc4ZwUcgr4v60REFhKBQtUH8cyPhF3ymY1RCiYX NPYJ0kJJ8kgsZ1eogGW9ZlKZH+RwRcSSec8gs0TFAN2nGizcwCbGUtV/ianiknUykJ2Z fJl4xVHww9Dh0SlYCk2WZgnCjOsEGaft6vat7jc8Hmw3UhbbwRegLyg5sOtyJQTBjlYP 60iA== In-Reply-To: <1352775704-9023-1-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, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: mhocko-AlSwsSmVLrQ@public.gmane.org, glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org, Tejun Heo Now that cgroup_unload_subsys() can tell whether the root css is online or not, we can safely call cgroup_unload_subsys() after idr init failure in cgroup_load_subsys(). Replace the manual unrolling and invoke cgroup_unload_subsys() on failure. This drops cgroup_mutex inbetween but should be safe as the subsystem will fail try_module_get() and thus can't be mounted inbetween. As this means that cgroup_unload_subsys() can be called before css_sets are rehashed, remove BUG_ON() on %NULL css_set->subsys[] from cgroup_unload_subsys(). Signed-off-by: Tejun Heo --- kernel/cgroup.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c3087f5..b42f63f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4400,8 +4400,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) */ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) { - int i; struct cgroup_subsys_state *css; + int i, ret; /* check name and function validity */ if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || @@ -4452,15 +4452,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) init_cgroup_css(css, ss, dummytop); /* init_idr must be after init_cgroup_css because it sets css->id. */ if (ss->use_id) { - int ret = cgroup_init_idr(ss, css); - if (ret) { - ss->destroy(dummytop); - dummytop->subsys[ss->subsys_id] = NULL; - subsys[ss->subsys_id] = NULL; - list_del_init(&ss->sibling); - mutex_unlock(&cgroup_mutex); - return ret; - } + ret = cgroup_init_idr(ss, css); + if (ret) + goto err_unload; } /* @@ -4498,6 +4492,12 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) /* success! */ mutex_unlock(&cgroup_mutex); return 0; + +err_unload: + mutex_unlock(&cgroup_mutex); + /* @ss can't be mounted here as try_module_get() would fail */ + cgroup_unload_subsys(ss); + return ret; } EXPORT_SYMBOL_GPL(cgroup_load_subsys); @@ -4548,7 +4548,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) struct css_set *cg = link->cg; hlist_del(&cg->hlist); - BUG_ON(!cg->subsys[ss->subsys_id]); cg->subsys[ss->subsys_id] = NULL; hhead = css_set_hash(cg->subsys); hlist_add_head(&cg->hlist, hhead); -- 1.7.11.7 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752314Ab2KMDCn (ORCPT ); Mon, 12 Nov 2012 22:02:43 -0500 Received: from mail-pb0-f46.google.com ([209.85.160.46]:46691 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754584Ab2KMDCf (ORCPT ); Mon, 12 Nov 2012 22:02:35 -0500 From: Tejun Heo To: lizefan@huawei.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Cc: mhocko@suse.cz, glommer@parallels.com, Tejun Heo Subject: [PATCH 13/17] cgroup: simplify cgroup_load_subsys() failure path Date: Mon, 12 Nov 2012 19:01:40 -0800 Message-Id: <1352775704-9023-14-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1352775704-9023-1-git-send-email-tj@kernel.org> References: <1352775704-9023-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that cgroup_unload_subsys() can tell whether the root css is online or not, we can safely call cgroup_unload_subsys() after idr init failure in cgroup_load_subsys(). Replace the manual unrolling and invoke cgroup_unload_subsys() on failure. This drops cgroup_mutex inbetween but should be safe as the subsystem will fail try_module_get() and thus can't be mounted inbetween. As this means that cgroup_unload_subsys() can be called before css_sets are rehashed, remove BUG_ON() on %NULL css_set->subsys[] from cgroup_unload_subsys(). Signed-off-by: Tejun Heo --- kernel/cgroup.c | 21 ++++++++++----------- 1 file changed, 10 insertions(+), 11 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index c3087f5..b42f63f 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4400,8 +4400,8 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss) */ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) { - int i; struct cgroup_subsys_state *css; + int i, ret; /* check name and function validity */ if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN || @@ -4452,15 +4452,9 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) init_cgroup_css(css, ss, dummytop); /* init_idr must be after init_cgroup_css because it sets css->id. */ if (ss->use_id) { - int ret = cgroup_init_idr(ss, css); - if (ret) { - ss->destroy(dummytop); - dummytop->subsys[ss->subsys_id] = NULL; - subsys[ss->subsys_id] = NULL; - list_del_init(&ss->sibling); - mutex_unlock(&cgroup_mutex); - return ret; - } + ret = cgroup_init_idr(ss, css); + if (ret) + goto err_unload; } /* @@ -4498,6 +4492,12 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss) /* success! */ mutex_unlock(&cgroup_mutex); return 0; + +err_unload: + mutex_unlock(&cgroup_mutex); + /* @ss can't be mounted here as try_module_get() would fail */ + cgroup_unload_subsys(ss); + return ret; } EXPORT_SYMBOL_GPL(cgroup_load_subsys); @@ -4548,7 +4548,6 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss) struct css_set *cg = link->cg; hlist_del(&cg->hlist); - BUG_ON(!cg->subsys[ss->subsys_id]); cg->subsys[ss->subsys_id] = NULL; hhead = css_set_hash(cg->subsys); hlist_add_head(&cg->hlist, hhead); -- 1.7.11.7