[Xen-devel] [PATCH 06/16] x86/monitor: fix: set msr_bitmap to NULL after xfree

[Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>]

Fix: set d->arch.monitor.msr_bitmap to NULL after xfree, as the equivalence of
it being NULL and xfreed is repeatedly presumed in the codebase. Along with this
change, also properly reposition an 'if' targeting the aforementioned msr_bitmap
when it is allocated and add likely/unlikely accordingly.

Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/monitor.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
index 29188e5..8f41f21 100644
--- a/xen/arch/x86/monitor.c
+++ b/xen/arch/x86/monitor.c
@@ -54,11 +54,12 @@ static inline void monitor_ctrlreg_disable_traps(struct 
domain *d)
 
 int monitor_init_domain(struct domain *d)
 {
-    if ( !d->arch.monitor.msr_bitmap )
+    if ( likely(!d->arch.monitor.msr_bitmap) )
+    {
         d->arch.monitor.msr_bitmap = xzalloc(struct monitor_msr_bitmap);
-
-    if ( !d->arch.monitor.msr_bitmap )
-        return -ENOMEM;
+        if ( unlikely(!d->arch.monitor.msr_bitmap) )
+            return -ENOMEM;
+    }
 
     return 0;
 }
@@ -66,6 +67,7 @@ int monitor_init_domain(struct domain *d)
 void monitor_cleanup_domain(struct domain *d)
 {
     xfree(d->arch.monitor.msr_bitmap);
+    d->arch.monitor.msr_bitmap = NULL;
 
     monitor_ctrlreg_disable_traps(d);
 
-- 
2.5.0


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