ACK: [SRU][Bionic][Patch 1/1] s390/qdio: clear intparm during shutdown

[Kleber Souza]

On 5/9/19 5:36 PM, frank.heimes at canonical.com wrote:
> From: Julian Wiedmann <jwi at linux.vnet.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1828394
> 
> During shutdown, qdio returns its ccw device back to control by the
> upper-layer driver. But there is a remote chance that by the time where the
> IRQ handler gets switched back, the interrupt for the preceding
> ccw_device_{clear,halt} hasn't been presented yet.
> Upper-layer drivers would then need to handle this IRQ - and since the IO
> is issued with an intparm, it could very well be confused with whatever
> intparm mechanism the driver uses itself (eg intparm == request address).
> 
> So when switching over the IRQ handler, also clear the intparm and have
> upper-layer drivers deal with any such delayed interrupt as if it was
> unsolicited.
> 
> Suggested-by: Sebastian Ott <sebott at linux.vnet.ibm.com>
> Signed-off-by: Julian Wiedmann <jwi at linux.vnet.ibm.com>
> Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
> (cherry picked from commit 89286320a236d245834075fa13adb0bdd827ecaa)
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>

Clean cherry-pick, limited to platform specific driver.

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
>  drivers/s390/cio/qdio_main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
> index d76df58..8842be6 100644
> --- a/drivers/s390/cio/qdio_main.c
> +++ b/drivers/s390/cio/qdio_main.c
> @@ -1218,8 +1218,10 @@ int qdio_shutdown(struct ccw_device *cdev, int how)
>  	qdio_shutdown_thinint(irq_ptr);
>  
>  	/* restore interrupt handler */
> -	if ((void *)cdev->handler == (void *)qdio_int_handler)
> +	if ((void *)cdev->handler == (void *)qdio_int_handler) {
>  		cdev->handler = irq_ptr->orig_handler;
> +		cdev->private->intparm = 0;
> +	}
>  	spin_unlock_irq(get_ccwdev_lock(cdev));
>  
>  	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_INACTIVE);
>