KVM: Add reading critical region for kvm_io_bus_read/write

Commit Message

Sheng Yang Dec. 6, 2010, 8:44 a.m. UTC

None

Patch

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c4ee364..3e71b91 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2228,28 +2228,36 @@  static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
 int kvm_io_bus_write(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 		     int len, const void *val)
 {
-	int i;
+	int i, idx, r = -EOPNOTSUPP;
 	struct kvm_io_bus *bus;
 
+	idx = srcu_read_lock(&kvm->srcu);
 	bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
 	for (i = 0; i < bus->dev_count; i++)
-		if (!kvm_iodevice_write(bus->devs[i], addr, len, val))
-			return 0;
-	return -EOPNOTSUPP;
+		if (!kvm_iodevice_write(bus->devs[i], addr, len, val)) {
+			r = 0;
+			break;
+		}
+	srcu_read_unlock(&kvm->srcu, idx);
+	return r;
 }
 
 /* kvm_io_bus_read - called under kvm->slots_lock */
 int kvm_io_bus_read(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 		    int len, void *val)
 {
-	int i;
+	int i, idx, r = -EOPNOTSUPP;
 	struct kvm_io_bus *bus;
 
+	idx = srcu_read_lock(&kvm->srcu);
 	bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
 	for (i = 0; i < bus->dev_count; i++)
-		if (!kvm_iodevice_read(bus->devs[i], addr, len, val))
-			return 0;
-	return -EOPNOTSUPP;
+		if (!kvm_iodevice_read(bus->devs[i], addr, len, val)) {
+			r = 0;
+			break;
+		}
+	srcu_read_unlock(&kvm->srcu, idx);
+	return r;
 }
 
 /* Caller must hold slots_lock. */