4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
[ Upstream commit 707693c8a498697aa8db240b93eb76ec62e30892 ]
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: 21e4902aea80 ("netlink: Lockless lookup with RCU grace...")
Reported-by: Subash Abhinov Kasiviswanathan <subashab@xxxxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Acked-by: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/netlink/af_netlink.c | 27 +++++++++++++++++++++++----
net/netlink/af_netlink.h | 2 ++
2 files changed, 25 insertions(+), 4 deletions(-)
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -924,14 +924,11 @@ static void netlink_skb_set_owner_r(stru
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);
}
@@ -960,6 +957,28 @@ static void netlink_sock_destruct(struct
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
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -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)
@@ -53,6 +54,7 @@ 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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