domain: domlist_update_lock can be static

For a long time (if not forever) this lock has been referenced only from a
single CU. Misra C:2012 rule 8.7 (which we didn't accept yet) wants us to
have such identifiers non-external.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

xen/common/domain.c

@@ -58,7 +58,7 @@ bool opt_dom0_vcpus_pin;
 boolean_param("dom0_vcpus_pin", opt_dom0_vcpus_pin);
 
 /* Protect updates/reads (resp.) of domain_list and domain_hash. */
-DEFINE_SPINLOCK(domlist_update_lock);
+static DEFINE_SPINLOCK(domlist_update_lock);
 DEFINE_RCU_READ_LOCK(domlist_read_lock);
 
 #define DOMAIN_HASH_SIZE 256

xen/include/xen/sched.h

@@ -697,8 +697,10 @@ static inline unsigned int domain_tot_pages(const struct domain *d)
     return d->tot_pages - d->extra_pages;
 }
 
-/* Protect updates/reads (resp.) of domain_list and domain_hash. */
-extern spinlock_t domlist_update_lock;
+/*
+ * Protect updates/reads (resp.) of domain_list and domain_hash, together with
+ * domlist_update_lock.
+ */
 extern rcu_read_lock_t domlist_read_lock;
 
 extern struct vcpu *idle_vcpu[NR_CPUS];