[Xen-devel] [PATCH 07/16] x86/vm-event: fix: call cleanup when init fails, to free partial allocs

[Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>]

From vm_event_init_domain(d), call vm_event_cleanup_domain(d) if per-vcpu
allocations failed -at some point- to cleanup partial allocations, if any were
done along the way.

Also minor adjustments: add unlikely in if's and add some comments.

Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/vm_event.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/vm_event.c b/xen/arch/x86/vm_event.c
index 6e19df8..22c63ea 100644
--- a/xen/arch/x86/vm_event.c
+++ b/xen/arch/x86/vm_event.c
@@ -23,20 +23,29 @@
 /* Implicitly serialized by the domctl lock. */
 int vm_event_init_domain(struct domain *d)
 {
+    int rc = 0;
     struct vcpu *v;
 
+    /* Per-vcpu initializations. */
     for_each_vcpu ( d, v )
     {
-        if ( v->arch.vm_event )
+        if ( unlikely(v->arch.vm_event) )
             continue;
 
         v->arch.vm_event = xzalloc(struct arch_vm_event);
-
-        if ( !v->arch.vm_event )
-            return -ENOMEM;
+        if ( unlikely(!v->arch.vm_event) )
+        {
+            rc = -ENOMEM;
+            goto err;
+        }
     }
 
-    return 0;
+err:
+    if ( unlikely(rc) )
+        /* On fail cleanup whatever resources have been partially allocated. */
+        vm_event_cleanup_domain(d);
+
+    return rc;
 }
 
 /*
@@ -47,6 +56,7 @@ void vm_event_cleanup_domain(struct domain *d)
 {
     struct vcpu *v;
 
+    /* Per-vcpu uninitializations. */
     for_each_vcpu ( d, v )
     {
         xfree(v->arch.vm_event);
-- 
2.5.0


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