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-rw-r--r--net/netlink/af_netlink.c27
-rw-r--r--net/netlink/af_netlink.h1
2 files changed, 27 insertions, 1 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 9db8bab..c2d585c 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2343,6 +2343,11 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
}
#endif
+ /* Record the max length of recvmsg() calls for future allocations */
+ nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
+ nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
+ 16384);
+
copied = data_skb->len;
if (len < copied) {
msg->msg_flags |= MSG_TRUNC;
@@ -2587,7 +2592,27 @@ static int netlink_dump(struct sock *sk)
if (!netlink_rx_is_mmaped(sk) &&
atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
goto errout_skb;
- skb = netlink_alloc_skb(sk, alloc_size, nlk->portid, GFP_KERNEL);
+
+ /* NLMSG_GOODSIZE is small to avoid high order allocations being
+ * required, but it makes sense to _attempt_ a 16K bytes allocation
+ * to reduce number of system calls on dump operations, if user
+ * ever provided a big enough buffer.
+ */
+ if (alloc_size < nlk->max_recvmsg_len) {
+ skb = netlink_alloc_skb(sk,
+ nlk->max_recvmsg_len,
+ nlk->portid,
+ GFP_KERNEL |
+ __GFP_NOWARN |
+ __GFP_NORETRY);
+ /* available room should be exact amount to avoid MSG_TRUNC */
+ if (skb)
+ skb_reserve(skb, skb_tailroom(skb) -
+ nlk->max_recvmsg_len);
+ }
+ if (!skb)
+ skb = netlink_alloc_skb(sk, alloc_size, nlk->portid,
+ GFP_KERNEL);
if (!skb)
goto errout_skb;
netlink_skb_set_owner_r(skb, sk);
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index acbd774..ed13a79 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -31,6 +31,7 @@ struct netlink_sock {
u32 ngroups;
unsigned long *groups;
unsigned long state;
+ size_t max_recvmsg_len;
wait_queue_head_t wait;
bool cb_running;
struct netlink_callback cb;
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