[Xen-devel] [PATCH 2/5] xen/domain: Break __domain_destroy() out of domain_create() and complete_domain_destroy()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This is the first step in making the destroy path idepotent, and using it in
place of the ad-hoc cleanup paths in the create path.

To begin with, the trivial free operations are broken out.  The rest of the
cleanup code will be moved as it is demonstrated (or made) to be idempotent.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
---
 xen/common/domain.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 43ab926..2253c2d 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -260,6 +260,23 @@ static int __init parse_extra_guest_irqs(const char *s)
 }
 custom_param("extra_guest_irqs", parse_extra_guest_irqs);
 
+/*
+ * Destroy a domain once all references to it have been dropped.  Used either
+ * from the RCU path, or from the domain_create() error path before the domain
+ * is inserted into the domlist.
+ */
+static void __domain_destroy(struct domain *d)
+{
+    BUG_ON(!d->is_dying);
+    BUG_ON(atomic_read(&d->refcnt) != DOMAIN_DESTROYED);
+
+    xfree(d->pbuf);
+
+    free_cpumask_var(d->dirty_cpumask);
+
+    free_domain_struct(d);
+}
+
 struct domain *domain_create(domid_t domid,
                              struct xen_domctl_createdomain *config,
                              bool is_priv)
@@ -437,7 +454,6 @@ struct domain *domain_create(domid_t domid,
     if ( hardware_domain == d )
         hardware_domain = old_hwdom;
     atomic_set(&d->refcnt, DOMAIN_DESTROYED);
-    xfree(d->pbuf);
 
     sched_destroy_domain(d);
 
@@ -462,8 +478,9 @@ struct domain *domain_create(domid_t domid,
         watchdog_domain_destroy(d);
     if ( init_status & INIT_xsm )
         xsm_free_security_domain(d);
-    free_cpumask_var(d->dirty_cpumask);
-    free_domain_struct(d);
+
+    __domain_destroy(d);
+
     return ERR_PTR(err);
 }
 
@@ -881,8 +898,6 @@ static void complete_domain_destroy(struct rcu_head *head)
     xfree(d->vm_event_share);
 #endif
 
-    xfree(d->pbuf);
-
     for ( i = d->max_vcpus - 1; i >= 0; i-- )
         if ( (v = d->vcpu[i]) != NULL )
         {
@@ -901,9 +916,9 @@ static void complete_domain_destroy(struct rcu_head *head)
     radix_tree_destroy(&d->pirq_tree, free_pirq_struct);
 
     xsm_free_security_domain(d);
-    free_cpumask_var(d->dirty_cpumask);
     xfree(d->vcpu);
-    free_domain_struct(d);
+
+    __domain_destroy(d);
 
     send_global_virq(VIRQ_DOM_EXC);
 }
-- 
2.1.4


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