[PATCH v4 05/13] KVM: s390: ucontrol: Add missing locking around gmap_remove_child()

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

gmap_remove_child() needs to be called while holding the children_lock
of the parent gmap. This was not the case in the error handling path of
kvm_arch_vcpu_create() for UCONTROL guests.

Fix by adding the missing lock.

Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 7b37e410d416..82c6c8632e1b 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3870,7 +3870,9 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 out_ucontrol_uninit:
 	if (kvm_is_ucontrol(vcpu->kvm)) {
+		spin_lock(&vcpu->kvm->arch.gmap->children_lock);
 		gmap_remove_child(vcpu->arch.gmap);
+		spin_unlock(&vcpu->kvm->arch.gmap->children_lock);
 		vcpu->arch.gmap = gmap_put(vcpu->arch.gmap);
 	}
 out_free_sie_block:
-- 
2.55.0