Alexis Berlemont wrote:
> Hi,
>
>
> > I've got a kernel module which creates a chrdev.
> > In the read file operation I have a interruptible_sleep_on.
> > Now I want to wake it up from an IPIPE interrupt handler
> > (i.e. unblock the read operation from user-space on the
> > chrdev), but I bet wake_up_interruptible is forbidden
> > in HRT context, isn't it ?
>
> Why not using a semaphore :
>
> in your read fops function :
>
> down_interruptible(pointer_read_sem);
>
> in your IPIPE interrupt handler:
>
> up(pointer_read_sem);
>
> In an interrupt handler, I think you can use a Linux semaphore. I am quite
> sure semaphores are used in the Xenomai pipe implementation.
For the "up" function to work properly, Linux scheduler data have to be
in a consistent state. But with the IPIPE patch, Linux may be preempted
by a higher priority domain at any point where hardware interrupts are
not disabled, and where scheduler data are not necessarily in a
consistent state.
One way to wake up a regular Linux thread from a higher priority domain
interrupt handler is to propagate this interrupt after HRT processing in
higher priority domains and run wake_up_interruptible from Linux domain
interrupt handler.
--
Gilles Chanteperdrix.
