Re: [uml-user] Any reason for a kernel thread not run after calling schedule()?

[Richard W. <ric...@gm...>]

On Wed, Oct 28, 2015 at 5:36 PM, Ricardo Nunes
<ric...@gm...> wrote:
> Hi,
>
> I'm making a UML driver to adapt a real driver to UML and hardware
> emulation.
>
> In this case I have a kernel thread trying to read a register, which is now
> done through a netlink channel to a userspace application (asynchronous
> response) but inside a synchronous function (the function that I'm
> implementing returns the register value). The first attempt was done doing:
>
> Kernel thread
>
> sleeping_task = current;
> set_current_state(TASK_INTERRUPTIBLE);
> schedule();
>
> Netlink new message callback
>
> wake_up_process(sleeping_task);
>
> But the kernel thread never runs again, unless I call schedule() in netlink
> callback function after wake_up_process, which will make that callback being
> blocked. I also tried using wait_queue but after the same result I saw the
> functions and realised that they also use schedule for putting the process
> to sleep.
>
> This worked in a "real" linux module (not with netlink callback, but between
> 2 kernel threads), I don't understand why shouldn't in UML. Any reason you
> might remember?

Can you please share your code?

-- 
Thanks,
//richard