On 13.03.24 09:14, Juergen Gross wrote:
Hello Juergen
> In bind_evtchn_to_irq_chip() don't increment the refcnt of the event
> channel blindly. In case the event channel is NOT refcounted, issue a
> warning instead.
>
> Add an additional safety net by doing the refcnt increment only if the
> caller has specified IRQF_SHARED in the irqflags parameter.
>
> Fixes: 9e90e58c11b7 ("xen: evtchn: Allow shared registration of IRQ handers")
> Signed-off-by: Juergen Gross <jgr...@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com>
> ---
> drivers/xen/events/events_base.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/xen/events/events_base.c
> b/drivers/xen/events/events_base.c
> index 2faa4bf78c7a..81effbd53dc5 100644
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -1190,7 +1190,7 @@ int xen_pirq_from_irq(unsigned irq)
> EXPORT_SYMBOL_GPL(xen_pirq_from_irq);
>
> static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip
> *chip,
> - struct xenbus_device *dev)
> + struct xenbus_device *dev, bool shared)
> {
> int ret = -ENOMEM;
> struct irq_info *info;
> @@ -1224,7 +1224,8 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t
> evtchn, struct irq_chip *chip,
> */
> bind_evtchn_to_cpu(info, 0, false);
> } else if (!WARN_ON(info->type != IRQT_EVTCHN)) {
> - info->refcnt++;
> + if (shared && !WARN_ON(info->refcnt < 0))
> + info->refcnt++;
> }
>
> ret = info->irq;
> @@ -1237,13 +1238,13 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t
> evtchn, struct irq_chip *chip,
>
> int bind_evtchn_to_irq(evtchn_port_t evtchn)
> {
> - return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip, NULL);
> + return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip, NULL, false);
> }
> EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
>
> int bind_evtchn_to_irq_lateeoi(evtchn_port_t evtchn)
> {
> - return bind_evtchn_to_irq_chip(evtchn, &xen_lateeoi_chip, NULL);
> + return bind_evtchn_to_irq_chip(evtchn, &xen_lateeoi_chip, NULL, false);
> }
> EXPORT_SYMBOL_GPL(bind_evtchn_to_irq_lateeoi);
>
> @@ -1295,7 +1296,8 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned
> int cpu)
>
> static int bind_interdomain_evtchn_to_irq_chip(struct xenbus_device *dev,
> evtchn_port_t remote_port,
> - struct irq_chip *chip)
> + struct irq_chip *chip,
> + bool shared)
> {
> struct evtchn_bind_interdomain bind_interdomain;
> int err;
> @@ -1307,14 +1309,14 @@ static int bind_interdomain_evtchn_to_irq_chip(struct
> xenbus_device *dev,
> &bind_interdomain);
>
> return err ? : bind_evtchn_to_irq_chip(bind_interdomain.local_port,
> - chip, dev);
> + chip, dev, shared);
> }
>
> int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
> evtchn_port_t remote_port)
> {
> return bind_interdomain_evtchn_to_irq_chip(dev, remote_port,
> - &xen_lateeoi_chip);
> + &xen_lateeoi_chip, false);
> }
> EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
>
> @@ -1430,7 +1432,8 @@ static int bind_evtchn_to_irqhandler_chip(evtchn_port_t
> evtchn,
> {
> int irq, retval;
>
> - irq = bind_evtchn_to_irq_chip(evtchn, chip, NULL);
> + irq = bind_evtchn_to_irq_chip(evtchn, chip, NULL,
> + irqflags & IRQF_SHARED);
> if (irq < 0)
> return irq;
> retval = request_irq(irq, handler, irqflags, devname, dev_id);
> @@ -1471,7 +1474,8 @@ static int bind_interdomain_evtchn_to_irqhandler_chip(
> {
> int irq, retval;
>
> - irq = bind_interdomain_evtchn_to_irq_chip(dev, remote_port, chip);
> + irq = bind_interdomain_evtchn_to_irq_chip(dev, remote_port, chip,
> + irqflags & IRQF_SHARED);
> if (irq < 0)
> return irq;
>
