Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / misc / cxl / base.c

diff --git a/kernel/drivers/misc/cxl/base.c b/kernel/drivers/misc/cxl/base.c
new file mode 100644 (file)
index 0000000..0654ad8
--- /dev/null
+++ b/kernel/drivers/misc/cxl/base.c
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2014 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/rcupdate.h>
+#include <asm/errno.h>
+#include <misc/cxl.h>
+#include "cxl.h"
+
+/* protected by rcu */
+static struct cxl_calls *cxl_calls;
+
+atomic_t cxl_use_count = ATOMIC_INIT(0);
+EXPORT_SYMBOL(cxl_use_count);
+
+#ifdef CONFIG_CXL_MODULE
+
+static inline struct cxl_calls *cxl_calls_get(void)
+{
+       struct cxl_calls *calls = NULL;
+
+       rcu_read_lock();
+       calls = rcu_dereference(cxl_calls);
+       if (calls && !try_module_get(calls->owner))
+               calls = NULL;
+       rcu_read_unlock();
+
+       return calls;
+}
+
+static inline void cxl_calls_put(struct cxl_calls *calls)
+{
+       BUG_ON(calls != cxl_calls);
+
+       /* we don't need to rcu this, as we hold a reference to the module */
+       module_put(cxl_calls->owner);
+}
+
+#else /* !defined CONFIG_CXL_MODULE */
+
+static inline struct cxl_calls *cxl_calls_get(void)
+{
+       return cxl_calls;
+}
+
+static inline void cxl_calls_put(struct cxl_calls *calls) { }
+
+#endif /* CONFIG_CXL_MODULE */
+
+void cxl_slbia(struct mm_struct *mm)
+{
+       struct cxl_calls *calls;
+
+       calls = cxl_calls_get();
+       if (!calls)
+               return;
+
+       if (cxl_ctx_in_use())
+           calls->cxl_slbia(mm);
+
+       cxl_calls_put(calls);
+}
+
+int register_cxl_calls(struct cxl_calls *calls)
+{
+       if (cxl_calls)
+               return -EBUSY;
+
+       rcu_assign_pointer(cxl_calls, calls);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(register_cxl_calls);
+
+void unregister_cxl_calls(struct cxl_calls *calls)
+{
+       BUG_ON(cxl_calls->owner != calls->owner);
+       RCU_INIT_POINTER(cxl_calls, NULL);
+       synchronize_rcu();
+}
+EXPORT_SYMBOL_GPL(unregister_cxl_calls);