From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755383Ab2CGKqo (ORCPT ); Wed, 7 Mar 2012 05:46:44 -0500 Received: from mailhub.sw.ru ([195.214.232.25]:46367 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241Ab2CGKqn (ORCPT ); Wed, 7 Mar 2012 05:46:43 -0500 From: Andrew Vagin To: Greg Kroah-Hartman , Kay Sievers Cc: avagin@openvz.org, linux-hotplug@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] uevent: send events in correct order according to seqnum (v3) Date: Wed, 7 Mar 2012 14:49:56 +0400 Message-Id: <1331117396-11600-1-git-send-email-avagin@openvz.org> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The queue handling in the udev daemon assumes that the events are ordered. Before this patch uevent_seqnum is incremented under sequence_lock, than an event is send uner uevent_sock_mutex. I want to say that code contained a window between incrementing seqnum and sending an event. This patch locks uevent_sock_mutex before incrementing uevent_seqnum. v2: delete sequence_lock, uevent_seqnum is protected by uevent_sock_mutex v3: unlock the mutex before the goto exit Thanks for Kay for the comments. Signed-off-by: Andrew Vagin --- lib/kobject_uevent.c | 19 +++++++++---------- 1 files changed, 9 insertions(+), 10 deletions(-) diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index e66e9b6..75cbdb5 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -29,16 +29,17 @@ u64 uevent_seqnum; char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; -static DEFINE_SPINLOCK(sequence_lock); #ifdef CONFIG_NET struct uevent_sock { struct list_head list; struct sock *sk; }; static LIST_HEAD(uevent_sock_list); -static DEFINE_MUTEX(uevent_sock_mutex); #endif +/* This lock protects uevent_seqnum and uevent_sock_list */ +static DEFINE_MUTEX(uevent_sock_mutex); + /* the strings here must match the enum in include/linux/kobject.h */ static const char *kobject_actions[] = { [KOBJ_ADD] = "add", @@ -136,7 +137,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, struct kobject *top_kobj; struct kset *kset; const struct kset_uevent_ops *uevent_ops; - u64 seq; int i = 0; int retval = 0; #ifdef CONFIG_NET @@ -243,17 +243,16 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, else if (action == KOBJ_REMOVE) kobj->state_remove_uevent_sent = 1; + mutex_lock(&uevent_sock_mutex); /* we will send an event, so request a new sequence number */ - spin_lock(&sequence_lock); - seq = ++uevent_seqnum; - spin_unlock(&sequence_lock); - retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)seq); - if (retval) + retval = add_uevent_var(env, "SEQNUM=%llu", (unsigned long long)++uevent_seqnum); + if (retval) { + mutex_unlock(&uevent_sock_mutex); goto exit; + } #if defined(CONFIG_NET) /* send netlink message */ - mutex_lock(&uevent_sock_mutex); list_for_each_entry(ue_sk, &uevent_sock_list, list) { struct sock *uevent_sock = ue_sk->sk; struct sk_buff *skb; @@ -290,8 +289,8 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, } else retval = -ENOMEM; } - mutex_unlock(&uevent_sock_mutex); #endif + mutex_unlock(&uevent_sock_mutex); /* call uevent_helper, usually only enabled during early boot */ if (uevent_helper[0] && !kobj_usermode_filter(kobj)) { -- 1.7.1