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Commit 7b60a18d authored by Andrew Vagin's avatar Andrew Vagin Committed by Greg Kroah-Hartman
Browse files

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



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: default avatarAndrew Vagin <avagin@openvz.org>
Tested-By: default avatarKay Sievers <kay.sievers@vrfy.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8b0372a2

lib/kobject_uevent.c

+9 −10
Original line number Diff line number Diff line
@@ -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)) {