[PATCH v3 29/29] eal: remove rte_smp_XX

[Stephen Hemminger <stephen@networkplumber.org>]

These functions were marked for deprecation over five years ago and
have no users left in the tree. Drop them from EAL, along with the
deprecation notice, and record the replacements in the release notes.

Checkpatch no longer looks for them: now that the macros are gone,
any remaining use is a compile error.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 devtools/checkpatches.sh               |  8 ----
 doc/guides/rel_notes/deprecation.rst   |  8 ----
 doc/guides/rel_notes/release_26_11.rst | 11 +++++
 lib/eal/arm/include/rte_atomic_32.h    |  6 ---
 lib/eal/arm/include/rte_atomic_64.h    |  6 ---
 lib/eal/include/generic/rte_atomic.h   | 61 --------------------------
 lib/eal/loongarch/include/rte_atomic.h |  6 ---
 lib/eal/ppc/include/rte_atomic.h       |  6 ---
 lib/eal/riscv/include/rte_atomic.h     |  6 ---
 lib/eal/x86/include/rte_atomic.h       |  4 --
 10 files changed, 11 insertions(+), 111 deletions(-)

diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
index 466e06410a..c52fb5d1b6 100755
--- a/devtools/checkpatches.sh
+++ b/devtools/checkpatches.sh
@@ -121,14 +121,6 @@ check_forbidden_additions() { # <patch>
 		-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
 		"$1" || res=1
 
-	# refrain from new additions of rte_smp_[r/w]mb()
-	awk -v FOLDERS="lib drivers app examples" \
-		-v EXPRESSIONS="rte_smp_(r|w)?mb\\\(" \
-		-v RET_ON_FAIL=1 \
-		-v MESSAGE='Using rte_smp_[r/w]mb' \
-		-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
-		"$1" || res=1
-
 	# refrain from using compiler __sync_xxx builtins
 	awk -v FOLDERS="lib drivers app examples" \
 		-v EXPRESSIONS="__sync_.*\\\(" \
diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 56a67c372e..600d789df8 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -39,14 +39,6 @@ Deprecation Notices
   as part of its internal API. All drivers will be adjusted
   to use the new unified VFIO container device assignment API.
 
-* rte_smp_*mb: These APIs provide full barrier functionality. However, many
-  use cases do not require full barriers. To support such use cases, DPDK has
-  adopted atomic operations from
-  https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html. These
-  operations and a new wrapper ``rte_atomic_thread_fence`` instead of
-  ``__atomic_thread_fence`` must be used for patches that need to be merged in
-  20.08 onwards. This change will not introduce any performance degradation.
-
 * mempool: The ``flushthresh`` field in ``struct rte_mempool_cache`` is obsolete,
   and will be removed in DPDK 26.11.
 
diff --git a/doc/guides/rel_notes/release_26_11.rst b/doc/guides/rel_notes/release_26_11.rst
index 16d3a90723..dd21c87afa 100644
--- a/doc/guides/rel_notes/release_26_11.rst
+++ b/doc/guides/rel_notes/release_26_11.rst
@@ -182,6 +182,17 @@ Removed Items
   ``cmpset`` and ``exchange``). Use the C11 ``rte_atomic_*_explicit``
   operations instead.
 
+* Removed SMP memory barriers:
+
+  * ``rte_smp_mb()`` replaced with ``rte_atomic_thread_fence(rte_memory_order_seq_cst)``
+  * ``rte_smp_rmb()`` replaced with ``rte_atomic_thread_fence(rte_memory_order_acquire)``
+  * ``rte_smp_wmb()`` replaced with ``rte_atomic_thread_fence(rte_memory_order_release)``
+
+  Some call sites became release stores or acquire loads instead of a
+  standalone fence. Barriers that order CPU accesses against a device,
+  rather than against another CPU, should use ``rte_io_wmb()`` and
+  ``rte_io_rmb()`` instead.
+
 * ethdev: Removed support for ethdev queue stats mapping.
 
   ``rte_eth_dev_set_tx_queue_stats_mapping`` and ``rte_eth_dev_set_rx_queue_stats_mapping``
diff --git a/lib/eal/arm/include/rte_atomic_32.h b/lib/eal/arm/include/rte_atomic_32.h
index 696a539fef..4115271091 100644
--- a/lib/eal/arm/include/rte_atomic_32.h
+++ b/lib/eal/arm/include/rte_atomic_32.h
@@ -17,12 +17,6 @@ extern "C" {
 
 #define	rte_rmb() __sync_synchronize()
 
-#define rte_smp_mb() rte_mb()
-
-#define rte_smp_wmb() rte_wmb()
-
-#define rte_smp_rmb() rte_rmb()
-
 #define rte_io_mb() rte_mb()
 
 #define rte_io_wmb() rte_wmb()
diff --git a/lib/eal/arm/include/rte_atomic_64.h b/lib/eal/arm/include/rte_atomic_64.h
index 9f790238df..604e777bcd 100644
--- a/lib/eal/arm/include/rte_atomic_64.h
+++ b/lib/eal/arm/include/rte_atomic_64.h
@@ -20,12 +20,6 @@ extern "C" {
 
 #define rte_rmb() asm volatile("dmb oshld" : : : "memory")
 
-#define rte_smp_mb() asm volatile("dmb ish" : : : "memory")
-
-#define rte_smp_wmb() asm volatile("dmb ishst" : : : "memory")
-
-#define rte_smp_rmb() asm volatile("dmb ishld" : : : "memory")
-
 #define rte_io_mb() rte_mb()
 
 #define rte_io_wmb() rte_wmb()
diff --git a/lib/eal/include/generic/rte_atomic.h b/lib/eal/include/generic/rte_atomic.h
index 23fc7a4d44..d659691db4 100644
--- a/lib/eal/include/generic/rte_atomic.h
+++ b/lib/eal/include/generic/rte_atomic.h
@@ -51,67 +51,6 @@ static inline void rte_wmb(void);
 static inline void rte_rmb(void);
 ///@}
 
-/** @name SMP Memory Barrier
- */
-///@{
-/**
- * General memory barrier between lcores
- *
- * Guarantees that the LOAD and STORE operations that precede the
- * rte_smp_mb() call are globally visible across the lcores
- * before the LOAD and STORE operations that follows it.
- *
- * @note
- *  This function is deprecated.
- *  It provides similar synchronization primitive as atomic fence,
- *  but has different syntax and memory ordering semantic. Hence
- *  deprecated for the simplicity of memory ordering semantics in use.
- *
- *  rte_atomic_thread_fence(rte_memory_order_acq_rel) should be used instead.
- */
-static inline void rte_smp_mb(void);
-
-/**
- * Write memory barrier between lcores
- *
- * Guarantees that the STORE operations that precede the
- * rte_smp_wmb() call are globally visible across the lcores
- * before the STORE operations that follows it.
- *
- * @note
- *  This function is deprecated.
- *  It provides similar synchronization primitive as atomic fence,
- *  but has different syntax and memory ordering semantic. Hence
- *  deprecated for the simplicity of memory ordering semantics in use.
- *
- *  rte_atomic_thread_fence(rte_memory_order_release) should be used instead.
- *  The fence also guarantees LOAD operations that precede the call
- *  are globally visible across the lcores before the STORE operations
- *  that follows it.
- */
-static inline void rte_smp_wmb(void);
-
-/**
- * Read memory barrier between lcores
- *
- * Guarantees that the LOAD operations that precede the
- * rte_smp_rmb() call are globally visible across the lcores
- * before the LOAD operations that follows it.
- *
- * @note
- *  This function is deprecated.
- *  It provides similar synchronization primitive as atomic fence,
- *  but has different syntax and memory ordering semantic. Hence
- *  deprecated for the simplicity of memory ordering semantics in use.
- *
- *  rte_atomic_thread_fence(rte_memory_order_acquire) should be used instead.
- *  The fence also guarantees LOAD operations that precede the call
- *  are globally visible across the lcores before the STORE operations
- *  that follows it.
- */
-static inline void rte_smp_rmb(void);
-///@}
-
 /** @name I/O Memory Barrier
  */
 ///@{
diff --git a/lib/eal/loongarch/include/rte_atomic.h b/lib/eal/loongarch/include/rte_atomic.h
index 785a452c9e..a789e3ab4d 100644
--- a/lib/eal/loongarch/include/rte_atomic.h
+++ b/lib/eal/loongarch/include/rte_atomic.h
@@ -18,12 +18,6 @@ extern "C" {
 
 #define rte_rmb()	rte_mb()
 
-#define rte_smp_mb()	rte_mb()
-
-#define rte_smp_wmb()	rte_mb()
-
-#define rte_smp_rmb()	rte_mb()
-
 #define rte_io_mb()	rte_mb()
 
 #define rte_io_wmb()	rte_mb()
diff --git a/lib/eal/ppc/include/rte_atomic.h b/lib/eal/ppc/include/rte_atomic.h
index d3bd50a11a..1e5c1747e6 100644
--- a/lib/eal/ppc/include/rte_atomic.h
+++ b/lib/eal/ppc/include/rte_atomic.h
@@ -24,12 +24,6 @@ extern "C" {
 
 #define	rte_rmb() asm volatile("sync" : : : "memory")
 
-#define rte_smp_mb() rte_mb()
-
-#define rte_smp_wmb() rte_wmb()
-
-#define rte_smp_rmb() rte_rmb()
-
 #define rte_io_mb() rte_mb()
 
 #define rte_io_wmb() rte_wmb()
diff --git a/lib/eal/riscv/include/rte_atomic.h b/lib/eal/riscv/include/rte_atomic.h
index 061b175f33..04c40e4e9b 100644
--- a/lib/eal/riscv/include/rte_atomic.h
+++ b/lib/eal/riscv/include/rte_atomic.h
@@ -23,12 +23,6 @@ extern "C" {
 
 #define rte_rmb()	asm volatile("fence r, r" : : : "memory")
 
-#define rte_smp_mb()	rte_mb()
-
-#define rte_smp_wmb()	rte_wmb()
-
-#define rte_smp_rmb()	rte_rmb()
-
 #define rte_io_mb()	asm volatile("fence iorw, iorw" : : : "memory")
 
 #define rte_io_wmb()	asm volatile("fence orw, ow" : : : "memory")
diff --git a/lib/eal/x86/include/rte_atomic.h b/lib/eal/x86/include/rte_atomic.h
index a46bedb0f0..0ed9421055 100644
--- a/lib/eal/x86/include/rte_atomic.h
+++ b/lib/eal/x86/include/rte_atomic.h
@@ -23,10 +23,6 @@
 
 #define	rte_rmb() _mm_lfence()
 
-#define rte_smp_wmb() rte_compiler_barrier()
-
-#define rte_smp_rmb() rte_compiler_barrier()
-
 #ifdef __cplusplus
 extern "C" {
 #endif
-- 
2.53.0