[PATCH net-next 1/7] net: add rps_tag_ptr type and helpers

[Eric Dumazet <edumazet@google.com>]

Add a new rps_tag_ptr type to encode a pointer and a size
to a power-of-two table.

Three helpers are added converting an rps_tag_ptr to:

1) A log of the size.

2) A mask : (size - 1).

3) A pointer to the array.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/net/rps-types.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 include/net/rps-types.h

diff --git a/include/net/rps-types.h b/include/net/rps-types.h
new file mode 100644
index 0000000000000000000000000000000000000000..6b90a66866c1f75dae768bed84a4eeb9ffb5fc1a
--- /dev/null
+++ b/include/net/rps-types.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _NET_RPS_TYPES_H
+#define _NET_RPS_TYPES_H
+
+/* Define a rps_tag_ptr:
+ * Low order 5 bits are used to store the ilog2(size) of an RPS table.
+ */
+typedef unsigned long rps_tag_ptr;
+
+static inline u8 rps_tag_to_log(rps_tag_ptr tag_ptr)
+{
+	return tag_ptr & 31U;
+}
+
+static inline u32 rps_tag_to_mask(rps_tag_ptr tag_ptr)
+{
+	return (1U << rps_tag_to_log(tag_ptr)) - 1;
+}
+
+static inline void *rps_tag_to_table(rps_tag_ptr tag_ptr)
+{
+	return (void *)(tag_ptr & ~31UL);
+}
+#endif /* _NET_RPS_TYPES_H */
-- 
2.53.0.473.g4a7958ca14-goog