Function intel_iommu_domain_init() may be concurrently called by upper
layer without serialization, so use atomic_t to protect domain id
allocation.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>