From 8c589ad5a9930e81760dc7f9f522e8054c3a5d4f Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <riastradh@NetBSD.org>
Date: Thu, 31 Mar 2022 02:13:23 +0000
Subject: [PATCH 30/49] linux/kref: Fix memory barriers and use
membar_release/acquire.
---
sys/external/bsd/drm2/include/linux/kref.h | 23 +++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/sys/external/bsd/drm2/include/linux/kref.h b/sys/external/bsd/drm2/include/linux/kref.h
index 00619bfad828..93fc01c950e4 100644
--- a/sys/external/bsd/drm2/include/linux/kref.h
+++ b/sys/external/bsd/drm2/include/linux/kref.h
@@ -58,10 +58,6 @@ kref_get(struct kref *kref)
atomic_inc_uint_nv(&kref->kr_count);
KASSERTMSG((count > 1), "getting released kref");
-
-#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_enter();
-#endif
}
static inline bool
@@ -76,10 +72,6 @@ kref_get_unless_zero(struct kref *kref)
} while (atomic_cas_uint(&kref->kr_count, count, (count + 1)) !=
count);
-#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_enter();
-#endif
-
return true;
}
@@ -89,7 +81,7 @@ kref_sub(struct kref *kref, unsigned int count, void (*release)(struct kref *))
unsigned int old, new;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
do {
@@ -100,6 +92,9 @@ kref_sub(struct kref *kref, unsigned int count, void (*release)(struct kref *))
} while (atomic_cas_uint(&kref->kr_count, old, new) != old);
if (new == 0) {
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+ membar_acquire();
+#endif
(*release)(kref);
return 1;
}
@@ -114,7 +109,7 @@ kref_put_lock(struct kref *kref, void (*release)(struct kref *),
unsigned int old, new;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
do {
@@ -123,6 +118,9 @@ kref_put_lock(struct kref *kref, void (*release)(struct kref *),
if (old == 1) {
spin_lock(interlock);
if (atomic_add_int_nv(&kref->kr_count, -1) == 0) {
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+ membar_acquire();
+#endif
(*release)(kref);
return 1;
}
@@ -149,7 +147,7 @@ kref_put_mutex(struct kref *kref, void (*release)(struct kref *),
unsigned int old, new;
#ifndef __HAVE_ATOMIC_AS_MEMBAR
- membar_exit();
+ membar_release();
#endif
do {
@@ -158,6 +156,9 @@ kref_put_mutex(struct kref *kref, void (*release)(struct kref *),
if (old == 1) {
mutex_lock(interlock);
if (atomic_add_int_nv(&kref->kr_count, -1) == 0) {
+#ifndef __HAVE_ATOMIC_AS_MEMBAR
+ membar_acquire();
+#endif
(*release)(kref);
return 1;
}
--
2.33.0