Commit 707693c8 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

netlink: Call cb->done from a worker thread 



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: 21e4902a ("netlink: Lockless lookup with RCU grace...")
Reported-by: default avatarSubash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 95c2027b

net/netlink/af_netlink.c

+23 −4
Original line number Diff line number Diff line
@@ -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

net/netlink/af_netlink.h

+2 −0
Original line number Diff line number Diff line
@@ -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)

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