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netlink: Call cb->done from a worker thread

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The cb->done interface expects to be called in process context.
This was broken by the netlink RCU conversion.  This patch fixes
it by adding a worker struct to make the cb->done call where
necessary.

Fixes: 21e4902aea ("netlink: Lockless lookup with RCU grace...")
Reported-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2016-11-28 19:22:12 +08:00 committed by David S. Miller
parent 95c2027bfe
commit 707693c8a4
2 changed files with 25 additions and 4 deletions
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27
net/netlink/af_netlink.c
View File

@ -322,14 +322,11 @@ static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
sk_mem_charge(sk, skb->truesize);
}
static void netlink_sock_destruct(struct sock *sk)
static void __netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (nlk->cb_running) {
if (nlk->cb.done)
nlk->cb.done(&nlk->cb);
module_put(nlk->cb.module);
kfree_skb(nlk->cb.skb);
}
@ -346,6 +343,28 @@ static void netlink_sock_destruct(struct sock *sk)
WARN_ON(nlk_sk(sk)->groups);
}
static void netlink_sock_destruct_work(struct work_struct *work)
{
struct netlink_sock *nlk = container_of(work, struct netlink_sock,
work);
nlk->cb.done(&nlk->cb);
__netlink_sock_destruct(&nlk->sk);
}
static void netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
if (nlk->cb_running && nlk->cb.done) {
INIT_WORK(&nlk->work, netlink_sock_destruct_work);
schedule_work(&nlk->work);
return;
}
__netlink_sock_destruct(sk);
}
/* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
* SMP. Look, when several writers sleep and reader wakes them up, all but one
* immediately hit write lock and grab all the cpus. Exclusive sleep solves

2
net/netlink/af_netlink.h
View File

@ -3,6 +3,7 @@
#include <linux/rhashtable.h>
#include <linux/atomic.h>
#include <linux/workqueue.h>
#include <net/sock.h>
#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
@ -33,6 +34,7 @@ struct netlink_sock {
struct rhash_head node;
struct rcu_head rcu;
struct work_struct work;
};
static inline struct netlink_sock *nlk_sk(struct sock *sk)