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uevent: send events in correct order according to seqnum (v3)

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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 <avagin@openvz.org>
Tested-By: Kay Sievers <kay.sievers@vrfy.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andrew Vagin 2012-03-07 14:49:56 +04:00 committed by Greg Kroah-Hartman
parent 8b0372a258
commit 7b60a18da3
1 changed files with 9 additions and 10 deletions
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19
lib/kobject_uevent.c
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@ -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)) {