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-rw-r--r--include/linux/rwbase_rt.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/include/linux/rwbase_rt.h b/include/linux/rwbase_rt.h
new file mode 100644
index 000000000000..1d264dd08625
--- /dev/null
+++ b/include/linux/rwbase_rt.h
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#ifndef _LINUX_RWBASE_RT_H
+#define _LINUX_RWBASE_RT_H
+
+#include <linux/rtmutex.h>
+#include <linux/atomic.h>
+
+#define READER_BIAS (1U << 31)
+#define WRITER_BIAS (1U << 30)
+
+struct rwbase_rt {
+ atomic_t readers;
+ struct rt_mutex_base rtmutex;
+};
+
+#define __RWBASE_INITIALIZER(name) \
+{ \
+ .readers = ATOMIC_INIT(READER_BIAS), \
+ .rtmutex = __RT_MUTEX_BASE_INITIALIZER(name.rtmutex), \
+}
+
+#define init_rwbase_rt(rwbase) \
+ do { \
+ rt_mutex_base_init(&(rwbase)->rtmutex); \
+ atomic_set(&(rwbase)->readers, READER_BIAS); \
+ } while (0)
+
+
+static __always_inline bool rw_base_is_locked(struct rwbase_rt *rwb)
+{
+ return atomic_read(&rwb->readers) != READER_BIAS;
+}
+
+static __always_inline bool rw_base_is_contended(struct rwbase_rt *rwb)
+{
+ return atomic_read(&rwb->readers) > 0;
+}
+
+#endif /* _LINUX_RWBASE_RT_H */