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kobject: reduce uevent_sock_mutex scope 

This is a followup of commit a3498436b3 ("netns: restrict uevents")

- uevent_sock_mutex no longer protects uevent_seqnum thanks
  to prior patch in the series.

- uevent_net_broadcast() can run without holding uevent_sock_mutex.

- Instead of grabbing uevent_sock_mutex before calling
  kobject_uevent_net_broadcast(), we can move the
  mutex_lock(&uevent_sock_mutex) to the place we iterate over
  uevent_sock_list : uevent_net_broadcast_untagged().

After this patch, typical netdevice creations and destructions
calling uevent_net_broadcast_tagged() no longer need to acquire
uevent_sock_mutex.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240214084829.684541-3-edumazet@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2024-02-14 08:48:29 +00:00 committed by Greg Kroah-Hartman
parent 2444a80c1c
commit 5c0941c55e
1 changed files with 3 additions and 6 deletions
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9
lib/kobject_uevent.c
View File

@ -42,10 +42,9 @@ struct uevent_sock {
#ifdef CONFIG_NET #ifdef CONFIG_NET
static LIST_HEAD(uevent_sock_list); static LIST_HEAD(uevent_sock_list);
#endif
/* This lock protects uevent_sock_list */ /* This lock protects uevent_sock_list */
static DEFINE_MUTEX(uevent_sock_mutex); static DEFINE_MUTEX(uevent_sock_mutex);
#endif
/* the strings here must match the enum in include/linux/kobject.h */ /* the strings here must match the enum in include/linux/kobject.h */
static const char *kobject_actions[] = { static const char *kobject_actions[] = {
@ -315,6 +314,7 @@ static int uevent_net_broadcast_untagged(struct kobj_uevent_env *env,
int retval = 0; int retval = 0;
/* send netlink message */ /* send netlink message */
mutex_lock(&uevent_sock_mutex);
list_for_each_entry(ue_sk, &uevent_sock_list, list) { list_for_each_entry(ue_sk, &uevent_sock_list, list) {
struct sock *uevent_sock = ue_sk->sk; struct sock *uevent_sock = ue_sk->sk;
@ -334,6 +334,7 @@ static int uevent_net_broadcast_untagged(struct kobj_uevent_env *env,
if (retval == -ENOBUFS || retval == -ESRCH) if (retval == -ENOBUFS || retval == -ESRCH)
retval = 0; retval = 0;
} }
mutex_unlock(&uevent_sock_mutex);
consume_skb(skb); consume_skb(skb);
return retval; return retval;
@ -589,10 +590,8 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
if (retval) if (retval)
goto exit; goto exit;
mutex_lock(&uevent_sock_mutex);
retval = kobject_uevent_net_broadcast(kobj, env, action_string, retval = kobject_uevent_net_broadcast(kobj, env, action_string,
devpath); devpath);
mutex_unlock(&uevent_sock_mutex);
#ifdef CONFIG_UEVENT_HELPER #ifdef CONFIG_UEVENT_HELPER
/* call uevent_helper, usually only enabled during early boot */ /* call uevent_helper, usually only enabled during early boot */
@ -743,9 +742,7 @@ static int uevent_net_rcv_skb(struct sk_buff *skb, struct nlmsghdr *nlh,
return -EPERM; return -EPERM;
} }
mutex_lock(&uevent_sock_mutex);
ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack); ret = uevent_net_broadcast(net->uevent_sock->sk, skb, extack);
mutex_unlock(&uevent_sock_mutex);
return ret; return ret;
} }