PCI/MSI: pci-xgene-msi: Fix CPU hotplug registration handling

The conversion to the new hotplug state machine introduced a regression
where a successful hotplug registration would be treated as an error,
effectively disabling the MSI driver forever.

Fix it by doing the proper check on the return value.

Fixes: 9c248f8896e6 ("PCI/xgene-msi: Convert to hotplug state machine")
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Duc Dang <dhdang@apm.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: stable@vger.kernel.org

path: root/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N

CONFIG_RCU_TRACE=n
CONFIG_SMP=y
CONFIG_NR_CPUS=4
CONFIG_HOTPLUG_CPU=y
CONFIG_PREEMPT_NONE=y
CONFIG_PREEMPT_VOLUNTARY=n
CONFIG_PREEMPT=n
CONFIG_RCU_EXPERT=y