[Qemu-devel] [PATCH v2 1/5] rcu: Add automatically released rcu_read_lock variant

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

RCU_READ_LOCK_AUTO takes the rcu_read_lock and then uses glib's
g_auto infrastructure (and thus whatever the compiler's hooks are) to
release it on all exits of the block.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/qemu/rcu.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
index 22876d1428..8768a7b60a 100644
--- a/include/qemu/rcu.h
+++ b/include/qemu/rcu.h
@@ -154,6 +154,24 @@ extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func);
       }),                                                                \
       (RCUCBFunc *)g_free);
 
+typedef void RCUReadAuto;
+static inline RCUReadAuto *rcu_read_auto_lock(void)
+{
+    rcu_read_lock();
+    /* Anything non-NULL causes the cleanup function to be called */
+    return (void *)0x1;
+}
+
+static inline void rcu_read_auto_unlock(RCUReadAuto *r)
+{
+    rcu_read_unlock();
+}
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(RCUReadAuto, rcu_read_auto_unlock)
+
+#define RCU_READ_LOCK_AUTO \
+    g_autoptr(RCUReadAuto) _rcu_read_auto = rcu_read_auto_lock()
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.21.0