From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41542) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UyYs8-0007dL-IJ for qemu-devel@nongnu.org; Sun, 14 Jul 2013 22:50:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UyYs7-0004XN-Ka for qemu-devel@nongnu.org; Sun, 14 Jul 2013 22:50:44 -0400 Received: from mail-pd0-x233.google.com ([2607:f8b0:400e:c02::233]:41551) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UyYs7-0004XB-DK for qemu-devel@nongnu.org; Sun, 14 Jul 2013 22:50:43 -0400 Received: by mail-pd0-f179.google.com with SMTP id q10so10224580pdj.38 for ; Sun, 14 Jul 2013 19:50:41 -0700 (PDT) From: Liu Ping Fan Date: Mon, 15 Jul 2013 10:49:15 +0800 Message-Id: <1373856556-22272-1-git-send-email-pingfank@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH 1/2] object: introduce Qref to abstract the refcnt interface List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Richard Henderson Qref is similar to kref. It hides the refcnt detail and provides a common interface. And this patch is based on the idiom of refcnt, and adopts some optimization about memory model, which finally falls back on gcc implementation. Signed-off-by: Liu Ping Fan --- include/qom/object.h | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/include/qom/object.h b/include/qom/object.h index 23fc048..2e165fb 100644 --- a/include/qom/object.h +++ b/include/qom/object.h @@ -18,6 +18,7 @@ #include #include #include "qemu/queue.h" +#include "qemu/osdep.h" struct Visitor; struct Error; @@ -363,6 +364,10 @@ struct ObjectClass ObjectUnparent *unparent; }; +typedef struct Qref { + int32_t count; +} Qref; + /** * Object: * @@ -1133,5 +1138,34 @@ int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque), */ Object *container_get(Object *root, const char *path); +static inline void qref_get(Qref *qref) +{ +#ifdef __ATOMIC_RELAXED + __atomic_fetch_add(&qref->count, 1, __ATOMIC_RELAXED); +#else + __sync_fetch_and_add(&qref->count, 1); +#endif +} + +typedef void (*ReleaseFn)(Qref *); +static inline void qref_put(Qref *qref, ReleaseFn release) +{ + int32_t i; + +#ifdef __ATOMIC_RELAXED + i = __atomic_fetch_add(&qref->count, -1, __ATOMIC_RELAXED); + g_assert(i > 0); + if (unlikely(i == 1)) { + __atomic_thread_fence(__ATOMIC_SEQ_CST); + release(qref); + } +#else + i = __sync_fetch_and_add(&qref->count, -1); + g_assert(i > 0); + if (unlikely(i == 1)) { + release(qref); + } +#endif +} #endif -- 1.8.1.4