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[Xen-devel] Re: [RFC PATCH 15/35] subarch support for controlling interrupt delivery
+/*
+ * The use of 'barrier' in the following reflects their use as local-lock
+ * operations. Reentrancy must be prevented (e.g., __cli()) /before/ following
+ * critical operations are executed. All critical operations must complete
+ * /before/ reentrancy is permitted (e.g., __sti()). Alpha architecture also
+ * includes these barriers, for example.
+ */
Seems like an odd comment to have in an i386 header file.
+#define __cli()
\
+do { \
+ struct vcpu_info *_vcpu; \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ _vcpu->evtchn_upcall_mask = 1; \
+ preempt_enable_no_resched(); \
+ barrier(); \
+} while (0)
Should be a real function
+#define __sti()
\
+do { \
+ struct vcpu_info *_vcpu; \
+ barrier(); \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ _vcpu->evtchn_upcall_mask = 0; \
+ barrier(); /* unmask then check (avoid races) */ \
+ if (unlikely(_vcpu->evtchn_upcall_pending)) \
+ force_evtchn_callback(); \
+ preempt_enable(); \
+} while (0)
Should be a real function
+#define __save_flags(x)
\
+do { \
+ struct vcpu_info *_vcpu; \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ (x) = _vcpu->evtchn_upcall_mask; \
+ preempt_enable(); \
+} while (0)
Should be a real function
+#define __restore_flags(x) \
+do { \
+ struct vcpu_info *_vcpu; \
+ barrier(); \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ if ((_vcpu->evtchn_upcall_mask = (x)) == 0) { \
+ barrier(); /* unmask then check (avoid races) */ \
+ if (unlikely(_vcpu->evtchn_upcall_pending)) \
+ force_evtchn_callback(); \
+ preempt_enable(); \
+ } else \
+ preempt_enable_no_resched(); \
+} while (0)
Should be a real function
+#define safe_halt() ((void)0)
+#define halt() ((void)0)
+
+#define __save_and_cli(x) \
+do { \
+ struct vcpu_info *_vcpu; \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ (x) = _vcpu->evtchn_upcall_mask; \
+ _vcpu->evtchn_upcall_mask = 1; \
+ preempt_enable_no_resched(); \
+ barrier(); \
+} while (0)
Should be a real function
+#define local_irq_save(x) __save_and_cli(x)
+#define local_irq_restore(x) __restore_flags(x)
+#define local_save_flags(x) __save_flags(x)
+#define local_irq_disable() __cli()
+#define local_irq_enable() __sti()
+
+/* Cannot use preempt_enable() here as we would recurse in preempt_sched(). */
+#define irqs_disabled()
\
+({ int ___x; \
+ struct vcpu_info *_vcpu; \
+ preempt_disable(); \
+ _vcpu = &HYPERVISOR_shared_info->vcpu_info[__vcpu_id]; \
+ ___x = (_vcpu->evtchn_upcall_mask != 0); \
+ preempt_enable_no_resched(); \
+ ___x; })
+
+#endif /* __KERNEL__ */
Should be a real function
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