KVM: set_memory_region: Remove unnecessary variable memslot

One such variable, slot, is enough for holding a pointer temporarily.
We also remove another local variable named slot, which is limited in
a block, since it is confusing to have the same name in this function.
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

virt/kvm/kvm_main.c

@@ -728,7 +728,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	int r;
 	gfn_t base_gfn;
 	unsigned long npages;
-	struct kvm_memory_slot *memslot, *slot;
+	struct kvm_memory_slot *slot;
 	struct kvm_memory_slot old, new;
 	struct kvm_memslots *slots = NULL, *old_memslots;
 
@@ -754,7 +754,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
 		goto out;
 
-	memslot = id_to_memslot(kvm->memslots, mem->slot);
+	slot = id_to_memslot(kvm->memslots, mem->slot);
 	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
 	npages = mem->memory_size >> PAGE_SHIFT;
 
@@ -765,7 +765,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (!npages)
 		mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
 
-	new = old = *memslot;
+	new = old = *slot;
 
 	new.id = mem->slot;
 	new.base_gfn = base_gfn;
@@ -786,7 +786,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		/* Check for overlaps */
 		r = -EEXIST;
 		kvm_for_each_memslot(slot, kvm->memslots) {
-			if (slot->id >= KVM_USER_MEM_SLOTS || slot == memslot)
+			if ((slot->id >= KVM_USER_MEM_SLOTS) ||
+			    (slot->id == mem->slot))
 				continue;
 			if (!((base_gfn + npages <= slot->base_gfn) ||
 			      (base_gfn >= slot->base_gfn + slot->npages)))
@@ -822,8 +823,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	}
 
 	if (!npages || base_gfn != old.base_gfn) {
-		struct kvm_memory_slot *slot;
-
 		r = -ENOMEM;
 		slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
 				GFP_KERNEL);