Hi all,
Actually I have this problem, which is more fundamental really. I
wanted to create a new message to send to the userspace. However everytime
I try to do so, using netlink_unicast, 0 bytes is sent. The listening
userspace application (using recvmsg) confirms that 0 bytes is received,
so I think a message IS sent from the kernel, but I don't understand why
I'm unable to send the entire message properly. Below is the code
skb_nl = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD), GFP_ATOMIC);
if (skb_nl == NULL) {
printk("%s: skb allocation fails!\n", __FUNCTION__);
goto out;
}
nlh = (struct nlmsghdr *)skb_nl->data;
/* Fill in the netlink message header */
nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
nlh->nlmsg_pid = 0;
nlh->nlmsg_flags = 0;
/* Fill in the netlink message payload */
strcpy(NLMSG_DATA(nlh), "Greeting from kernel!");
NETLINK_CB(skb_nl).groups = 0; /* not in mcast group */
NETLINK_CB(skb_nl).pid = 0; /* from kernel */
NETLINK_CB(skb_nl).dst_pid = nlq_pid; /* pid of userspace process */
NETLINK_CB(skb_nl).dst_groups = 0; /* unicast */
err = netlink_unicast(nl_sk, skb_nl, nlq_pid, MSG_DONTWAIT);
I really do hope someone can shed some light from this problem.
Thank you in advanced.
cheers
Chiang
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