Re: [PATCH v5 07/12] Maintain memslot version number

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 On 07/19/2010 06:30 PM, Gleb Natapov wrote:
Code that depends on particular memslot layout can track changes and
adjust to new layout.


diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index c13cc48..c74ffc0 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -177,6 +177,7 @@ struct kvm {
  	raw_spinlock_t requests_lock;
  	struct mutex slots_lock;
  	struct mm_struct *mm; /* userspace tied to this vm */
+	u32 memslot_version;
  	struct kvm_memslots *memslots;
  	struct srcu_struct srcu;
  #ifdef CONFIG_KVM_APIC_ARCHITECTURE
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b78b794..292514c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -733,6 +733,7 @@ skip_lpage:
  	slots->memslots[mem->slot] = new;
  	old_memslots = kvm->memslots;
  	rcu_assign_pointer(kvm->memslots, slots);
+	kvm->memslot_version++;
  	synchronize_srcu_expedited(&kvm->srcu);

  	kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);

How does this interact with rcu? Nothing enforces consistency between rcu_dereference(kvm->memslots) and kvm->memslot_version.

Should probably be rcu_dereference(kvm->memslots)->version.

--
error compiling committee.c: too many arguments to function

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