@@ -851,14 +851,11 @@ static void complete_domain_destroy(struct rcu_head *head)
void domain_destroy(struct domain *d)
{
struct domain **pd;
- atomic_t old = ATOMIC_INIT(0);
- atomic_t new = ATOMIC_INIT(DOMAIN_DESTROYED);
BUG_ON(!d->is_dying);
/* May be already destroyed, or get_domain() can race us. */
- old = atomic_compareandswap(old, new, &d->refcnt);
- if ( _atomic_read(old) != 0 )
+ if ( atomic_cmpxchg(&d->refcnt, 0, DOMAIN_DESTROYED) != 0 )
return;
cpupool_rm_domain(d);
@@ -138,14 +138,6 @@ static inline void _atomic_set(atomic_t *v, int i)
# error "unknown ARM variant"
#endif
-static inline atomic_t atomic_compareandswap(
- atomic_t old, atomic_t new, atomic_t *v)
-{
- atomic_t rc;
- rc.counter = __cmpxchg(&v->counter, old.counter, new.counter, sizeof(int));
- return rc;
-}
-
#endif /* __ARCH_ARM_ATOMIC__ */
/*
* Local variables:
@@ -272,12 +272,4 @@ static inline int atomic_add_negative(int i, atomic_t *v)
return c;
}
-static inline atomic_t atomic_compareandswap(
- atomic_t old, atomic_t new, atomic_t *v)
-{
- atomic_t rc;
- rc.counter = __cmpxchg(&v->counter, old.counter, new.counter, sizeof(int));
- return rc;
-}
-
#endif /* __ARCH_X86_ATOMIC__ */
new file mode 100644
@@ -0,0 +1,43 @@
+/******************************************************************************
+ * atomic.h
+ *
+ * Generic atomic variables.
+ *
+ * Copyright (c) 2015 Citrix R&D Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ATOMIC_H__
+#define __ATOMIC_H__
+
+#include <asm/atomic.h>
+
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+ return cmpxchg(&v->counter, old, new);
+}
+
+/**
+ * atomic_add_return - add integer and return
+ * @i: integer value to add
+ * @v: pointer of type atomic_t
+ *
+ * Atomically adds @i to @v and returns @i + @v
+ */
+static inline int atomic_add_return(int i, atomic_t *v)
+{
+ return i + arch_fetch_and_add(&v->counter, i);
+}
+
+#endif /* __ATOMIC_H__ */
@@ -17,7 +17,7 @@
#include <xen/mm.h>
#include <xen/smp.h>
#include <xen/perfc.h>
-#include <asm/atomic.h>
+#include <xen/atomic.h>
#include <xen/wait.h>
#include <public/xen.h>
#include <public/domctl.h>
@@ -481,16 +481,15 @@ extern struct vcpu *idle_vcpu[NR_CPUS];
*/
static always_inline int get_domain(struct domain *d)
{
- atomic_t old, new, seen = d->refcnt;
+ int old, seen = atomic_read(&d->refcnt);
do
{
old = seen;
- if ( unlikely(_atomic_read(old) & DOMAIN_DESTROYED) )
+ if ( unlikely(old & DOMAIN_DESTROYED) )
return 0;
- _atomic_set(&new, _atomic_read(old) + 1);
- seen = atomic_compareandswap(old, new, &d->refcnt);
+ seen = atomic_cmpxchg(&d->refcnt, old, old + 1);
}
- while ( unlikely(_atomic_read(seen) != _atomic_read(old)) );
+ while ( unlikely(seen != old) );
return 1;
}
atomic_compareandswap() used atomic_t as the new, old and returned values which is less convinient than using just int. Signed-off-by: David Vrabel <david.vrabel@citrix.com> --- xen/common/domain.c | 5 +---- xen/include/asm-arm/atomic.h | 8 -------- xen/include/asm-x86/atomic.h | 8 -------- xen/include/xen/atomic.h | 43 +++++++++++++++++++++++++++++++++++++++++++ xen/include/xen/sched.h | 11 +++++------ 5 files changed, 49 insertions(+), 26 deletions(-) create mode 100644 xen/include/xen/atomic.h