iothread: fix epollfd leak in the process of delIOThread

When we call addIOThread, the epollfd created in aio_context_setup,
but not close it in the process of delIOThread, so the epollfd will leak.

Reorder the code in aio_epoll_disable and reuse it.

Signed-off-by: Jie Wang <wangjie88@huawei.com>
Message-Id: <1526517763-11108-1-git-send-email-wangjie88@huawei.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
[Mention change to aio_epoll_disable in commit message. - Fam]
Signed-off-by: Fam Zheng <famz@redhat.com>

include/block/aio.h

@@ -554,6 +554,14 @@ static inline bool in_aio_context_home_thread(AioContext *ctx)
  */
 void aio_context_setup(AioContext *ctx);
 
+/**
+ * aio_context_destroy:
+ * @ctx: the aio context
+ *
+ * Destroy the aio context.
+ */
+void aio_context_destroy(AioContext *ctx);
+
 /**
  * aio_context_set_poll_params:
  * @ctx: the aio context

util/aio-posix.c

@@ -45,11 +45,11 @@ struct AioHandler
 
 static void aio_epoll_disable(AioContext *ctx)
 {
-    ctx->epoll_available = false;
-    if (!ctx->epoll_enabled) {
+    ctx->epoll_enabled = false;
+    if (!ctx->epoll_available) {
         return;
     }
-    ctx->epoll_enabled = false;
+    ctx->epoll_available = false;
     close(ctx->epollfd);
 }
 
@@ -713,6 +713,13 @@ void aio_context_setup(AioContext *ctx)
 #endif
 }
 
+void aio_context_destroy(AioContext *ctx)
+{
+#ifdef CONFIG_EPOLL_CREATE1
+    aio_epoll_disable(ctx);
+#endif
+}
+
 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
                                  int64_t grow, int64_t shrink, Error **errp)
 {

util/aio-win32.c

@@ -407,6 +407,10 @@ void aio_context_setup(AioContext *ctx)
 {
 }
 
+void aio_context_destroy(AioContext *ctx)
+{
+}
+
 void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns,
                                  int64_t grow, int64_t shrink, Error **errp)
 {

util/async.c

@@ -298,6 +298,7 @@ aio_ctx_finalize(GSource     *source)
     qemu_rec_mutex_destroy(&ctx->lock);
     qemu_lockcnt_destroy(&ctx->list_lock);
     timerlistgroup_deinit(&ctx->tlg);
+    aio_context_destroy(ctx);
 }
 
 static GSourceFuncs aio_source_funcs = {