Jens Kramel wrote:
Hi guys,
I'm writing a kernel module that uses inet-sockets and I have been looking
for something like the select(2) call for some days now, but couldn't find
anything. What I want is to specify several sockets and wait (using a
timeout) for incoming data simultaneously.
Would be really great if someone could give me a hint (or maybe even a
little code example? ;)
One way to do this is to use a waitqueue. AFAIK, this is how TUX kernel
web server handles multiple sockets with multiple threads attached to a
waitqueue. Another way is to use the MSG_DONTWAIT in recvmsg, and check
the return value to decide what to do. A common programming idiom is
(copied from tux):
read_again:
init_sync_kiocb(&iocb, NULL);
len = sock->sk->sk_prot->recvmsg(&iocb, sock->sk, &msg, max_size,
MSG_DONTWAIT, MSG_PEEK, NULL);
if (-EIOCBQUEUED == len)
len = wait_on_sync_kiocb(&iocb);
if ((len == -EAGAIN) || (len == -ERESTARTSYS)) {
if (!signal_pending(current)) {
len = 0;
goto out;
}
flush_all_signals();
goto read_again;
}
There might be a way to directly call do_select, but I am not sure.
--
Pradeep Padala
http://ppadala.blogspot.com
--
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