From b9bf16adfbadbadaf6d7f31a7375354c21e28887 Mon Sep 17 00:00:00 2001
From: Hans Petter Selasky <hselasky@FreeBSD.org>
Date: Mon, 20 Apr 2020 16:21:37 +0000
Subject: [PATCH] Implement the atomic fetch add unless functions for the
 LinuxKPI.

MFC after:	1 week
Sponsored by:	Mellanox Technologies
---
 .../linuxkpi/common/include/asm/atomic-long.h      | 14 ++++++++++++++
 sys/compat/linuxkpi/common/include/asm/atomic.h    | 14 ++++++++++++++
 sys/compat/linuxkpi/common/include/asm/atomic64.h  | 14 ++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/sys/compat/linuxkpi/common/include/asm/atomic-long.h b/sys/compat/linuxkpi/common/include/asm/atomic-long.h
index 108d7f4f7b3..e2bea06c095 100644
--- a/sys/compat/linuxkpi/common/include/asm/atomic-long.h
+++ b/sys/compat/linuxkpi/common/include/asm/atomic-long.h
@@ -110,6 +110,20 @@ atomic_long_add_unless(atomic_long_t *v, long a, long u)
 	return (c != u);
 }
 
+static inline long
+atomic_long_fetch_add_unless(atomic_long_t *v, long a, long u)
+{
+	long c = atomic_long_read(v);
+
+	for (;;) {
+		if (unlikely(c == u))
+			break;
+		if (likely(atomic_fcmpset_long(&v->counter, &c, c + a)))
+			break;
+	}
+	return (c);
+}
+
 static inline long
 atomic_long_dec_and_test(atomic_long_t *v)
 {
diff --git a/sys/compat/linuxkpi/common/include/asm/atomic.h b/sys/compat/linuxkpi/common/include/asm/atomic.h
index f9a9149186a..fff06f61d85 100644
--- a/sys/compat/linuxkpi/common/include/asm/atomic.h
+++ b/sys/compat/linuxkpi/common/include/asm/atomic.h
@@ -119,6 +119,20 @@ atomic_add_unless(atomic_t *v, int a, int u)
 	return (c != u);
 }
 
+static inline int
+atomic_fetch_add_unless(atomic_t *v, int a, int u)
+{
+	int c = atomic_read(v);
+
+	for (;;) {
+		if (unlikely(c == u))
+			break;
+		if (likely(atomic_fcmpset_int(&v->counter, &c, c + a)))
+			break;
+	}
+	return (c);
+}
+
 static inline void
 atomic_clear_mask(unsigned int mask, atomic_t *v)
 {
diff --git a/sys/compat/linuxkpi/common/include/asm/atomic64.h b/sys/compat/linuxkpi/common/include/asm/atomic64.h
index 7ba3e979200..c60117b5cb8 100644
--- a/sys/compat/linuxkpi/common/include/asm/atomic64.h
+++ b/sys/compat/linuxkpi/common/include/asm/atomic64.h
@@ -103,6 +103,20 @@ atomic64_add_unless(atomic64_t *v, int64_t a, int64_t u)
 	return (c != u);
 }
 
+static inline int64_t
+atomic64_fetch_add_unless(atomic64_t *v, int64_t a, int64_t u)
+{
+	int64_t c = atomic64_read(v);
+
+	for (;;) {
+		if (unlikely(c == u))
+			break;
+		if (likely(atomic_fcmpset_64(&v->counter, &c, c + a)))
+			break;
+	}
+	return (c);
+}
+
 static inline int64_t
 atomic64_xchg(atomic64_t *v, int64_t i)
 {