[PATCH v6 4/6] eal: add atomic bit operations

[Mattias Rönnblom]

Add atomic bit test/set/clear/assign/flip and
test-and-set/clear/assign/flip functions.

All atomic bit functions allow (and indeed, require) the caller to
specify a memory order.

Signed-off-by: Mattias Rönnblom <mattias.ronnblom at ericsson.com>
Acked-by: Morten Brørup <mb at smartsharesystems.com>
Acked-by: Tyler Retzlaff <roretzla at linux.microsoft.com>
Acked-by: Jack Bond-Preston <jack.bond-preston at foss.arm.com>

--

PATCH v3:
 * Introduce __RTE_GEN_BIT_ATOMIC_*() 'qualifier' argument already in
   this patch (Jack Bond-Preston).
 * Refer to volatile bit op functions as variants instead of families
   (macro parameter naming).
 * Update release notes.

PATCH:
 * Add missing macro #undef for C++ version of atomic bit flip.

RFC v7:
 * Replace compare-exchange-based rte_bitset_atomic_test_and_*() and
   flip() with implementations that use the previous value as returned
   by the atomic fetch function.
 * Reword documentation to match the non-atomic macro variants.
 * Remove pointer to <rte_stdatomic.h> for memory model documentation,
   since there is no documentation for that API.

RFC v6:
 * Have rte_bit_atomic_test() accept const-marked bitsets.

RFC v4:
 * Add atomic bit flip.
 * Mark macro-generated private functions experimental.

RFC v3:
 * Work around lack of C++ support for _Generic (Tyler Retzlaff).

RFC v2:
 o Add rte_bit_atomic_test_and_assign() (for consistency).
 o Fix bugs in rte_bit_atomic_test_and_[set|clear]().
 o Use <rte_stdatomics.h> to support MSVC.
---
 doc/guides/rel_notes/release_24_11.rst |  17 +
 lib/eal/include/rte_bitops.h           | 415 +++++++++++++++++++++++++
 2 files changed, 432 insertions(+)

diff --git a/doc/guides/rel_notes/release_24_11.rst b/doc/guides/rel_notes/release_24_11.rst
index 0ff70d9057..3111b1e4c0 100644
--- a/doc/guides/rel_notes/release_24_11.rst
+++ b/doc/guides/rel_notes/release_24_11.rst
@@ -56,6 +56,23 @@ New Features
      =======================================================
 
 
+* **Extended bit operations API.**
+
+  The support for bit-level operations on single 32- and 64-bit words
+  in <rte_bitops.h> has been extended with two families of
+  semantically well-defined functions.
+
+  rte_bit_[test|set|clear|assign|flip]() functions provide excellent
+  performance (by avoiding restricting the compiler and CPU), but give
+  no guarantees in regards to memory ordering or atomicity.
+
+  rte_bit_atomic_*() provides atomic bit-level operations, including
+  the possibility to specifying memory ordering constraints.
+
+  The new public API elements are polymorphic, using the _Generic-
+  based macros (for C) and function overloading (in C++ translation
+  units).
+
 Removed Items
 -------------
 
diff --git a/lib/eal/include/rte_bitops.h b/lib/eal/include/rte_bitops.h
index 6915b945ba..3ad6795fd1 100644
--- a/lib/eal/include/rte_bitops.h
+++ b/lib/eal/include/rte_bitops.h
@@ -21,6 +21,7 @@
 
 #include <rte_compat.h>
 #include <rte_debug.h>
+#include <rte_stdatomic.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -226,6 +227,204 @@ extern "C" {
 		 uint32_t *: __rte_bit_flip32,				\
 		 uint64_t *: __rte_bit_flip64)(addr, nr)
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Test if a particular bit in a word is set with a particular memory
+ * order.
+ *
+ * Test a bit with the resulting memory load ordered as per the
+ * specified memory order.
+ *
+ * @param addr
+ *   A pointer to the word to query.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ * @return
+ *   Returns true if the bit is set, and false otherwise.
+ */
+#define rte_bit_atomic_test(addr, nr, memory_order)			\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_test32,			\
+		 const uint32_t *: __rte_bit_atomic_test32,		\
+		 uint64_t *: __rte_bit_atomic_test64,			\
+		 const uint64_t *: __rte_bit_atomic_test64)(addr, nr,	\
+							    memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically set bit in word.
+ *
+ * Generic selection macro to atomically set bit specified by @c nr in
+ * the word pointed to by @c addr to '1', with the memory ordering as
+ * specified by @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ */
+#define rte_bit_atomic_set(addr, nr, memory_order)			\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_set32,			\
+		 uint64_t *: __rte_bit_atomic_set64)(addr, nr, memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically clear bit in word.
+ *
+ * Generic selection macro to atomically set bit specified by @c nr in
+ * the word pointed to by @c addr to '0', with the memory ordering as
+ * specified by @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ */
+#define rte_bit_atomic_clear(addr, nr, memory_order)			\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_clear32,			\
+		 uint64_t *: __rte_bit_atomic_clear64)(addr, nr, memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically assign a value to bit in word.
+ *
+ * Generic selection macro to atomically set bit specified by @c nr in the
+ * word pointed to by @c addr to the value indicated by @c value, with
+ * the memory ordering as specified with @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param value
+ *   The new value of the bit - true for '1', or false for '0'.
+ * @param memory_order
+ *   The memory order to use.
+ */
+#define rte_bit_atomic_assign(addr, nr, value, memory_order)		\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_assign32,			\
+		 uint64_t *: __rte_bit_atomic_assign64)(addr, nr, value, \
+							memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically flip bit in word.
+ *
+ * Generic selection macro to atomically negate the value of the bit
+ * specified by @c nr in the word pointed to by @c addr to the value
+ * indicated by @c value, with the memory ordering as specified with
+ * @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ */
+#define rte_bit_atomic_flip(addr, nr, memory_order)			\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_flip32,			\
+		 uint64_t *: __rte_bit_atomic_flip64)(addr, nr, memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically test and set a bit in word.
+ *
+ * Generic selection macro to atomically test and set bit specified by
+ * @c nr in the word pointed to by @c addr to '1', with the memory
+ * ordering as specified with @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ * @return
+ *   Returns true if the bit was set, and false otherwise.
+ */
+#define rte_bit_atomic_test_and_set(addr, nr, memory_order)		\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_test_and_set32,		\
+		 uint64_t *: __rte_bit_atomic_test_and_set64)(addr, nr,	\
+							      memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically test and clear a bit in word.
+ *
+ * Generic selection macro to atomically test and clear bit specified
+ * by @c nr in the word pointed to by @c addr to '0', with the memory
+ * ordering as specified with @c memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param memory_order
+ *   The memory order to use.
+ * @return
+ *   Returns true if the bit was set, and false otherwise.
+ */
+#define rte_bit_atomic_test_and_clear(addr, nr, memory_order)		\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_test_and_clear32,		\
+		 uint64_t *: __rte_bit_atomic_test_and_clear64)(addr, nr, \
+								memory_order)
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Atomically test and assign a bit in word.
+ *
+ * Generic selection macro to atomically test and assign bit specified
+ * by @c nr in the word pointed to by @c addr the value specified by
+ * @c value, with the memory ordering as specified with @c
+ * memory_order.
+ *
+ * @param addr
+ *   A pointer to the word to modify.
+ * @param nr
+ *   The index of the bit.
+ * @param value
+ *   The new value of the bit - true for '1', or false for '0'.
+ * @param memory_order
+ *   The memory order to use.
+ * @return
+ *   Returns true if the bit was set, and false otherwise.
+ */
+#define rte_bit_atomic_test_and_assign(addr, nr, value, memory_order)	\
+	_Generic((addr),						\
+		 uint32_t *: __rte_bit_atomic_test_and_assign32,	\
+		 uint64_t *: __rte_bit_atomic_test_and_assign64)(addr, nr, \
+								 value, \
+								 memory_order)
+
 #define __RTE_GEN_BIT_TEST(variant, qualifier, size)			\
 	__rte_experimental						\
 	static inline bool						\
@@ -299,6 +498,146 @@ extern "C" {
 __RTE_GEN_BIT_OPS_SIZE(32)
 __RTE_GEN_BIT_OPS_SIZE(64)
 
+#define __RTE_GEN_BIT_ATOMIC_TEST(variant, qualifier, size)		\
+	__rte_experimental						\
+	static inline bool						\
+	__rte_bit_atomic_ ## variant ## test ## size(const qualifier uint ## size ## _t *addr, \
+						     unsigned int nr, int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		const qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr = \
+			(const qualifier RTE_ATOMIC(uint ## size ## _t) *)addr;	\
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		return rte_atomic_load_explicit(a_addr, memory_order) & mask; \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_SET(variant, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_atomic_ ## variant ## set ## size(qualifier uint ## size ## _t *addr, \
+					      unsigned int nr, int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr =	\
+			(qualifier RTE_ATOMIC(uint ## size ## _t) *)addr; \
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		rte_atomic_fetch_or_explicit(a_addr, mask, memory_order); \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_CLEAR(variant, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_atomic_ ## variant ## clear ## size(qualifier uint ## size ## _t *addr,	\
+						unsigned int nr, int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr =	\
+			(qualifier RTE_ATOMIC(uint ## size ## _t) *)addr; \
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		rte_atomic_fetch_and_explicit(a_addr, ~mask, memory_order); \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_FLIP(variant, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_atomic_ ## variant ## flip ## size(qualifier uint ## size ## _t *addr, \
+					       unsigned int nr, int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr =	\
+			(qualifier RTE_ATOMIC(uint ## size ## _t) *)addr; \
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		rte_atomic_fetch_xor_explicit(a_addr, mask, memory_order); \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_ASSIGN(variant, qualifier, size)		\
+	__rte_experimental						\
+	static inline void						\
+	__rte_bit_atomic_## variant ## assign ## size(qualifier uint ## size ## _t *addr, \
+						unsigned int nr, bool value, \
+						int memory_order)	\
+	{								\
+		if (value)						\
+			__rte_bit_atomic_ ## variant ## set ## size(addr, nr, memory_order); \
+		else							\
+			__rte_bit_atomic_ ## variant ## clear ## size(addr, nr, \
+								     memory_order); \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_TEST_AND_SET(variant, qualifier, size)	\
+	__rte_experimental						\
+	static inline bool						\
+	__rte_bit_atomic_ ## variant ## test_and_set ## size(qualifier uint ## size ## _t *addr, \
+						       unsigned int nr,	\
+						       int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr =	\
+			(qualifier RTE_ATOMIC(uint ## size ## _t) *)addr; \
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		uint ## size ## _t prev;				\
+									\
+		prev = rte_atomic_fetch_or_explicit(a_addr, mask,	\
+						    memory_order);	\
+									\
+		return prev & mask;					\
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_TEST_AND_CLEAR(variant, qualifier, size)	\
+	__rte_experimental						\
+	static inline bool						\
+	__rte_bit_atomic_ ## variant ## test_and_clear ## size(qualifier uint ## size ## _t *addr, \
+							 unsigned int nr, \
+							 int memory_order) \
+	{								\
+		RTE_ASSERT(nr < size);					\
+									\
+		qualifier RTE_ATOMIC(uint ## size ## _t) *a_addr =	\
+			(qualifier RTE_ATOMIC(uint ## size ## _t) *)addr; \
+		uint ## size ## _t mask = (uint ## size ## _t)1 << nr;	\
+		uint ## size ## _t prev;				\
+									\
+	        prev = rte_atomic_fetch_and_explicit(a_addr, ~mask,	\
+						     memory_order);	\
+									\
+		return prev & mask;					\
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_TEST_AND_ASSIGN(variant, qualifier, size)	\
+	__rte_experimental						\
+	static inline bool						\
+	__rte_bit_atomic_ ## variant ## test_and_assign ## size(qualifier uint ## size ## _t *addr, \
+							  unsigned int nr, \
+							  bool value,	\
+							  int memory_order) \
+	{								\
+		if (value)						\
+			return __rte_bit_atomic_ ## variant ## test_and_set ## size(addr, nr, memory_order); \
+		else							\
+			return __rte_bit_atomic_ ## variant ## test_and_clear ## size(addr, nr, memory_order); \
+	}
+
+#define __RTE_GEN_BIT_ATOMIC_OPS(variant, qualifier, size)	\
+	__RTE_GEN_BIT_ATOMIC_TEST(variant, qualifier, size)	\
+	__RTE_GEN_BIT_ATOMIC_SET(variant, qualifier, size)	\
+	__RTE_GEN_BIT_ATOMIC_CLEAR(variant, qualifier, size)	\
+	__RTE_GEN_BIT_ATOMIC_ASSIGN(variant, qualifier, size)	\
+	__RTE_GEN_BIT_ATOMIC_TEST_AND_SET(variant, qualifier, size) \
+	__RTE_GEN_BIT_ATOMIC_TEST_AND_CLEAR(variant, qualifier, size) \
+	__RTE_GEN_BIT_ATOMIC_TEST_AND_ASSIGN(variant, qualifier, size) \
+	__RTE_GEN_BIT_ATOMIC_FLIP(variant, qualifier, size)
+
+#define __RTE_GEN_BIT_ATOMIC_OPS_SIZE(size) \
+	__RTE_GEN_BIT_ATOMIC_OPS(,, size)
+
+__RTE_GEN_BIT_ATOMIC_OPS_SIZE(32)
+__RTE_GEN_BIT_ATOMIC_OPS_SIZE(64)
+
 /*------------------------ 32-bit relaxed operations ------------------------*/
 
 /**
@@ -994,6 +1333,15 @@ rte_log2_u64(uint64_t v)
 #undef rte_bit_assign
 #undef rte_bit_flip
 
+#undef rte_bit_atomic_test
+#undef rte_bit_atomic_set
+#undef rte_bit_atomic_clear
+#undef rte_bit_atomic_assign
+#undef rte_bit_atomic_flip
+#undef rte_bit_atomic_test_and_set
+#undef rte_bit_atomic_test_and_clear
+#undef rte_bit_atomic_test_and_assign
+
 #define __RTE_BIT_OVERLOAD_SZ_2(fun, qualifier, size, arg1_type, arg1_name) \
 	static inline void						\
 	rte_bit_ ## fun(qualifier uint ## size ## _t *addr,		\
@@ -1037,12 +1385,79 @@ rte_log2_u64(uint64_t v)
 	__RTE_BIT_OVERLOAD_SZ_3(fun, qualifier, 64, arg1_type, arg1_name, \
 				arg2_type, arg2_name)
 
+#define __RTE_BIT_OVERLOAD_SZ_3R(fun, qualifier, size, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name)	\
+	static inline ret_type						\
+	rte_bit_ ## fun(uint ## size ## _t *addr, arg1_type arg1_name,	\
+			arg2_type arg2_name)				\
+	{								\
+		return __rte_bit_ ## fun ## size(addr, arg1_name, arg2_name); \
+	}
+
+#define __RTE_BIT_OVERLOAD_3R(fun, qualifier, ret_type, arg1_type, arg1_name, \
+			      arg2_type, arg2_name)			\
+	__RTE_BIT_OVERLOAD_SZ_3R(fun, qualifier, 32, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name)	\
+	__RTE_BIT_OVERLOAD_SZ_3R(fun, qualifier, 64, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name)
+
+#define __RTE_BIT_OVERLOAD_SZ_4(fun, qualifier, size, arg1_type, arg1_name, \
+				arg2_type, arg2_name, arg3_type, arg3_name) \
+	static inline void						\
+	rte_bit_ ## fun(uint ## size ## _t *addr, arg1_type arg1_name,	\
+			arg2_type arg2_name, arg3_type arg3_name)	\
+	{								\
+		__rte_bit_ ## fun ## size(addr, arg1_name, arg2_name,	\
+					  arg3_name);		      \
+	}
+
+#define __RTE_BIT_OVERLOAD_4(fun, qualifier, arg1_type, arg1_name, arg2_type, \
+			     arg2_name, arg3_type, arg3_name)		\
+	__RTE_BIT_OVERLOAD_SZ_4(fun, qualifier, 32, arg1_type, arg1_name, \
+				arg2_type, arg2_name, arg3_type, arg3_name) \
+	__RTE_BIT_OVERLOAD_SZ_4(fun, qualifier, 64, arg1_type, arg1_name, \
+				arg2_type, arg2_name, arg3_type, arg3_name)
+
+#define __RTE_BIT_OVERLOAD_SZ_4R(fun, qualifier, size, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name, arg3_type, \
+				 arg3_name)				\
+	static inline ret_type						\
+	rte_bit_ ## fun(uint ## size ## _t *addr, arg1_type arg1_name,	\
+			arg2_type arg2_name, arg3_type arg3_name)	\
+	{								\
+		return __rte_bit_ ## fun ## size(addr, arg1_name, arg2_name, \
+						 arg3_name);		\
+	}
+
+#define __RTE_BIT_OVERLOAD_4R(fun, qualifier, ret_type, arg1_type, arg1_name, \
+			      arg2_type, arg2_name, arg3_type, arg3_name) \
+	__RTE_BIT_OVERLOAD_SZ_4R(fun, qualifier, 32, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name, arg3_type, \
+				 arg3_name)				\
+	__RTE_BIT_OVERLOAD_SZ_4R(fun, qualifier, 64, ret_type, arg1_type, \
+				 arg1_name, arg2_type, arg2_name, arg3_type, \
+				 arg3_name)
+
 __RTE_BIT_OVERLOAD_2R(test, const, bool, unsigned int, nr)
 __RTE_BIT_OVERLOAD_2(set,, unsigned int, nr)
 __RTE_BIT_OVERLOAD_2(clear,, unsigned int, nr)
 __RTE_BIT_OVERLOAD_3(assign,, unsigned int, nr, bool, value)
 __RTE_BIT_OVERLOAD_2(flip,, unsigned int, nr)
 
+__RTE_BIT_OVERLOAD_3R(atomic_test, const, bool, unsigned int, nr,
+		      int, memory_order)
+__RTE_BIT_OVERLOAD_3(atomic_set,, unsigned int, nr, int, memory_order)
+__RTE_BIT_OVERLOAD_3(atomic_clear,, unsigned int, nr, int, memory_order)
+__RTE_BIT_OVERLOAD_4(atomic_assign,, unsigned int, nr, bool, value,
+		     int, memory_order)
+__RTE_BIT_OVERLOAD_3(atomic_flip,, unsigned int, nr, int, memory_order)
+__RTE_BIT_OVERLOAD_3R(atomic_test_and_set,, bool, unsigned int, nr,
+		      int, memory_order)
+__RTE_BIT_OVERLOAD_3R(atomic_test_and_clear,, bool, unsigned int, nr,
+		      int, memory_order)
+__RTE_BIT_OVERLOAD_4R(atomic_test_and_assign,, bool, unsigned int, nr,
+		      bool, value, int, memory_order)
+
 #endif
 
 #endif /* _RTE_BITOPS_H_ */
-- 
2.34.1