[PATCH V5 06/14] powerpc/vas: Setup thread IRQ handler per VAS instance

[Michael Neuling]

>  /*
> + * Process CRBs that we receive on the fault window.
> + */
> +irqreturn_t vas_fault_handler(int irq, void *data)
> +{
> +	struct vas_instance *vinst = data;
> +	struct coprocessor_request_block buf, *crb;
> +	struct vas_window *window;
> +	void *fifo;
> +
> +	/*
> +	 * VAS can interrupt with multiple page faults. So process all
> +	 * valid CRBs within fault FIFO until reaches invalid CRB.
> +	 * NX updates nx_fault_stamp in CRB and pastes in fault FIFO.
> +	 * kernel retrives send window from parition send window ID
> +	 * (pswid) in nx_fault_stamp. So pswid should be non-zero and
> +	 * use this to check whether CRB is valid.
> +	 * After reading CRB entry, it is reset with 0's in fault FIFO.
> +	 *
> +	 * In case kernel receives another interrupt with different page
> +	 * fault and CRBs are processed by the previous handling, will be
> +	 * returned from this function when it sees invalid CRB (means 0's).
> +	 */
> +	do {
> +		mutex_lock(&vinst->mutex);

This isn't going to work.

>From Documentation/locking/mutex-design.rst

    - Mutexes may not be used in hardware or software interrupt
      contexts such as tasklets and timers.

Mikey