This is a note to let you know that I've just added the patch titled
uevent: send events in correct order according to seqnum (v3)
to my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also will be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 7b60a18da393ed70db043a777fd9e6d5363077c4 Mon Sep 17 00:00:00 2001
From: Andrew Vagin <[email protected]>
Date: Wed, 7 Mar 2012 14:49:56 +0400
Subject: 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: Andrew Vagin <[email protected]>
Tested-By: Kay Sievers <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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)) {
--
1.7.9
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