Messages in this thread | | | Date | Sat, 4 Apr 2009 02:54:48 +0530 | Subject | Issue with netlink implementation | From | Keyoor Khristi <> |
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Hi All,
We are facing an issue with netlink implementation. We are sending the data from user space to kernel space. a kernel thread gets the data from netlink socket (via skb_recv_datagram). After doing little bit processing we give the skb to driver. driver sends the data and frees the skb. Sometimes we observe that the writer thread in userspace gets stuck writing a packet and doesnt come out. We traced the problem to netlink_attachskb. When a packet is sent on the netlink socket netlink_attachskb is called to add the skb to the queue. when there is not enough space, the thread is added to nlk->wait queue and issues schedule_timeout. it doesnt come out of it as no other thread awakens it. It seems when the driver frees the skb, the data is freed and the receive space is made available in the destructor but the thread waiting is not awaken. This is causing the problem we're seeing. I think the netlink implementation in af_netlink.c can be enhanced. In netlink_attachskb, after invoking skb_set_owner_r we should change the skb->destructor to point to newly added function netlink_rfree. When skb is freed, netlink_rfree function can issue sock_rfree and awaken the threads waiting on nlk->wait queue.
Please let me know what you think about it. I'm not sure if i've sent the email to correct forum. If i should be sending to another forum, please tell me.
Regards, K
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