[Xen-devel] [PATCH] common/vm_event: Initialize vm_event lists on domain creation

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

Pending livepatch code wants to check if the vm_event wait queues
are active, and this is made harder by the fact that they were
previously only initialized some time after the domain was created,
in vm_event_enable(). This patch initializes the lists immediately
after xzalloc()ating the vm_event memory, in domain_create(), in
the newly added init_domain_vm_event() function.

Signed-off-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
---
 xen/common/domain.c        |  5 ++---
 xen/common/vm_event.c      | 23 ++++++++++++++++++++---
 xen/include/xen/vm_event.h |  2 ++
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index b22aacc..89a8f1d 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -362,11 +362,10 @@ struct domain *domain_create(domid_t domid, unsigned int 
domcr_flags,
 
         poolid = 0;
 
-        err = -ENOMEM;
-        d->vm_event = xzalloc(struct vm_event_per_domain);
-        if ( !d->vm_event )
+        if ( (err = init_domain_vm_event(d)) != 0 )
             goto fail;
 
+        err = -ENOMEM;
         d->pbuf = xzalloc_array(char, DOMAIN_PBUF_SIZE);
         if ( !d->pbuf )
             goto fail;
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 9291db6..294ddd7 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -39,6 +39,26 @@
 #define vm_event_ring_lock(_ved)       spin_lock(&(_ved)->ring_lock)
 #define vm_event_ring_unlock(_ved)     spin_unlock(&(_ved)->ring_lock)
 
+int init_domain_vm_event(struct domain *d)
+{
+    d->vm_event = xzalloc(struct vm_event_per_domain);
+
+    if ( !d->vm_event )
+        return -ENOMEM;
+
+#ifdef CONFIG_HAS_MEM_PAGING
+    init_waitqueue_head(&d->vm_event->paging.wq);
+#endif
+
+    init_waitqueue_head(&d->vm_event->monitor.wq);
+
+#ifdef CONFIG_HAS_MEM_SHARING
+    init_waitqueue_head(&d->vm_event->share.wq);
+#endif
+
+    return 0;
+}
+
 static int vm_event_enable(
     struct domain *d,
     xen_domctl_vm_event_op_t *vec,
@@ -93,9 +113,6 @@ static int vm_event_enable(
     /* Save the pause flag for this particular ring. */
     ved->pause_flag = pause_flag;
 
-    /* Initialize the last-chance wait queue. */
-    init_waitqueue_head(&ved->wq);
-
     vm_event_ring_unlock(ved);
     return 0;
 
diff --git a/xen/include/xen/vm_event.h b/xen/include/xen/vm_event.h
index 2fb3951..482243e 100644
--- a/xen/include/xen/vm_event.h
+++ b/xen/include/xen/vm_event.h
@@ -80,6 +80,8 @@ void vm_event_set_registers(struct vcpu *v, 
vm_event_response_t *rsp);
 
 void vm_event_monitor_next_interrupt(struct vcpu *v);
 
+int init_domain_vm_event(struct domain *d);
+
 #endif /* __VM_EVENT_H__ */
 
 /*
-- 
1.9.1


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