Re: Waking up kernel thread blocked in sock_recvmsg

[Andi Kleen <ak@suse.de>]

"Steven French" <sfrench@us.ibm.com> writes:

> What is the recommended, safe way to wake up a kernel thread blocked in
> sock_recvmsg (other than sending data to it or pulling the network cable
> out of the wall and generating network errors).   I have tried various
> approaches in kernel sock_close, sock_release even wake_up_process.    When
> I want to free my captive kernel threads this thread is typically blocked
> in tcp_recv_data (on a blocking read of a tcp v4 socket).  I am not certain
> that it is not waking up and promptly going back to sleep but it is
> certainly not returning to the caller until it really gets data.

You could send it a signal. 

Or alternatively use non blocking sockets and sleep yourself on the socket
wait queue.

-Andi