From 5881181d8c80609034204c128975fbbac77baaed Mon Sep 17 00:00:00 2001
From: Matt Macy <mmacy@FreeBSD.org>
Date: Thu, 3 Jan 2019 23:06:05 +0000
Subject: [PATCH] mp_ring: avoid items offset difference between iflib and
 mp_ring on architectures without 64-bit atomics

Reported by:	Augustin Cavalier <waddlesplash@gmail.com>
---
 sys/net/mp_ring.c | 12 ++++--------
 sys/net/mp_ring.h |  6 +++++-
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/sys/net/mp_ring.c b/sys/net/mp_ring.c
index 0a1956f1168a..8e04e6142e35 100644
--- a/sys/net/mp_ring.c
+++ b/sys/net/mp_ring.c
@@ -37,10 +37,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <machine/cpu.h>
 
-#if defined(__powerpc__) || defined(__mips__) || defined(__i386__)
-#define NO_64BIT_ATOMICS
-#endif
-
 #if defined(__i386__)
 #define atomic_cmpset_acq_64 atomic_cmpset_64
 #define atomic_cmpset_rel_64 atomic_cmpset_64
@@ -101,7 +97,7 @@ state_to_flags(union ring_state s, int abdicate)
 	return (BUSY);
 }
 
-#ifdef NO_64BIT_ATOMICS
+#ifdef MP_RING_NO_64BIT_ATOMICS
 static void
 drain_ring_locked(struct ifmp_ring *r, union ring_state os, uint16_t prev, int budget)
 {
@@ -291,7 +287,7 @@ ifmp_ring_alloc(struct ifmp_ring **pr, int size, void *cookie, mp_ring_drain_t d
 	}
 
 	*pr = r;
-#ifdef NO_64BIT_ATOMICS
+#ifdef MP_RING_NO_64BIT_ATOMICS
 	mtx_init(&r->lock, "mp_ring lock", NULL, MTX_DEF);
 #endif
 	return (0);
@@ -325,7 +321,7 @@ ifmp_ring_free(struct ifmp_ring *r)
  *
  * Returns an errno.
  */
-#ifdef NO_64BIT_ATOMICS
+#ifdef MP_RING_NO_64BIT_ATOMICS
 int
 ifmp_ring_enqueue(struct ifmp_ring *r, void **items, int n, int budget, int abdicate)
 {
@@ -503,7 +499,7 @@ ifmp_ring_check_drainage(struct ifmp_ring *r, int budget)
 	ns.flags = BUSY;
 
 
-#ifdef NO_64BIT_ATOMICS
+#ifdef MP_RING_NO_64BIT_ATOMICS
 	mtx_lock(&r->lock);
 	if (r->state != os.state) {
 		mtx_unlock(&r->lock);
diff --git a/sys/net/mp_ring.h b/sys/net/mp_ring.h
index ebec3ae487d7..6dea325dc435 100644
--- a/sys/net/mp_ring.h
+++ b/sys/net/mp_ring.h
@@ -40,6 +40,10 @@ typedef u_int (*mp_ring_drain_t)(struct ifmp_ring *, u_int, u_int);
 typedef u_int (*mp_ring_can_drain_t)(struct ifmp_ring *);
 typedef void (*mp_ring_serial_t)(struct ifmp_ring *);
 
+#if defined(__powerpc__) || defined(__mips__) || defined(__i386__)
+#define MP_RING_NO_64BIT_ATOMICS
+#endif
+
 struct ifmp_ring {
 	volatile uint64_t	state __aligned(CACHE_LINE_SIZE);
 
@@ -54,7 +58,7 @@ struct ifmp_ring {
 	counter_u64_t		stalls;
 	counter_u64_t		restarts;	/* recovered after stalling */
 	counter_u64_t		abdications;
-#ifdef NO_64BIT_ATOMICS
+#ifdef MP_RING_NO_64BIT_ATOMICS
 	struct mtx		lock;
 #endif
 	void * volatile		items[] __aligned(CACHE_LINE_SIZE);