Modify the netlink code so that SOCK_VMIO has the desired effect on the
user-space side of the connection.
Modify sys_{send,recv}msg to use sk->sk_allocation instead of GFP_KERNEL,
this should not change existing behaviour because the default of
sk->sk_allocation is GFP_KERNEL, and no user-space exposed socket would
have it any different at this time.
This change allows the system calls to succeed for SOCK_VMIO sockets
(who have sk->sk_allocation |= GFP_EMERGENCY) even under extreme memory
pressure.
Since netlink_sendmsg is used to transfer msgs from user- to kernel-space
treat the skb allocation there as a receive allocation.
Also export netlink_lookup, this is needed to locate the kernel side struct
sock object associated with the user-space netlink socket.
Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
CC: David Miller <[EMAIL PROTECTED]>
CC: Mike Christie <[EMAIL PROTECTED]>
---
include/linux/netlink.h | 1 +
net/compat.c | 2 +-
net/netlink/af_netlink.c | 8 +++++---
net/socket.c | 6 +++---
4 files changed, 10 insertions(+), 7 deletions(-)
Index: linux-2.6/net/netlink/af_netlink.c
===================================================================
--- linux-2.6.orig/net/netlink/af_netlink.c
+++ linux-2.6/net/netlink/af_netlink.c
@@ -199,7 +199,7 @@ netlink_unlock_table(void)
wake_up(&nl_table_wait);
}
-static __inline__ struct sock *netlink_lookup(int protocol, u32 pid)
+__inline__ struct sock *netlink_lookup(int protocol, u32 pid)
{
struct nl_pid_hash *hash = &nl_table[protocol].hash;
struct hlist_head *head;
@@ -1147,7 +1147,7 @@ static int netlink_sendmsg(struct kiocb
if (len > sk->sk_sndbuf - 32)
goto out;
err = -ENOBUFS;
- skb = alloc_skb(len, GFP_KERNEL);
+ skb = __alloc_skb(len, GFP_KERNEL, SKB_ALLOC_RX);
if (skb==NULL)
goto out;
@@ -1178,7 +1178,8 @@ static int netlink_sendmsg(struct kiocb
if (dst_group) {
atomic_inc(&skb->users);
- netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL);
+ netlink_broadcast(sk, skb, dst_pid, dst_group,
+ sk->sk_allocation);
}
err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT);
@@ -1788,6 +1789,7 @@ panic:
core_initcall(netlink_proto_init);
+EXPORT_SYMBOL(netlink_lookup);
EXPORT_SYMBOL(netlink_ack);
EXPORT_SYMBOL(netlink_run_queue);
EXPORT_SYMBOL(netlink_queue_skip);
Index: linux-2.6/net/socket.c
===================================================================
--- linux-2.6.orig/net/socket.c
+++ linux-2.6/net/socket.c
@@ -1790,7 +1790,7 @@ asmlinkage long sys_sendmsg(int fd, stru
err = -ENOMEM;
iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
if (msg_sys.msg_iovlen > UIO_FASTIOV) {
- iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
+ iov = sock_kmalloc(sock->sk, iov_size, sock->sk->sk_allocation);
if (!iov)
goto out_put;
}
@@ -1818,7 +1818,7 @@ asmlinkage long sys_sendmsg(int fd, stru
} else if (ctl_len) {
if (ctl_len > sizeof(ctl))
{
- ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
+ ctl_buf = sock_kmalloc(sock->sk, ctl_len,
sock->sk->sk_allocation);
if (ctl_buf == NULL)
goto out_freeiov;
}
@@ -1891,7 +1891,7 @@ asmlinkage long sys_recvmsg(int fd, stru
err = -ENOMEM;
iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
if (msg_sys.msg_iovlen > UIO_FASTIOV) {
- iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
+ iov = sock_kmalloc(sock->sk, iov_size, sock->sk->sk_allocation);
if (!iov)
goto out_put;
}
Index: linux-2.6/include/linux/netlink.h
===================================================================
--- linux-2.6.orig/include/linux/netlink.h
+++ linux-2.6/include/linux/netlink.h
@@ -150,6 +150,7 @@ struct netlink_skb_parms
#define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds)
+extern struct sock *netlink_lookup(int protocol, __u32 pid);
extern struct sock *netlink_kernel_create(int unit, unsigned int groups, void
(*input)(struct sock *sk, int len), struct module *module);
extern void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err);
extern int netlink_has_listeners(struct sock *sk, unsigned int group);
Index: linux-2.6/net/compat.c
===================================================================
--- linux-2.6.orig/net/compat.c
+++ linux-2.6/net/compat.c
@@ -170,7 +170,7 @@ int cmsghdr_from_user_compat_to_kern(str
* from the user.
*/
if (kcmlen > stackbuf_size)
- kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen, GFP_KERNEL);
+ kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen,
sk->sk_allocation);
if (kcmsg == NULL)
return -ENOBUFS;
--
-
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