[Qemu-devel] [PATCH] Revert "aio: clean up now-unused functions"

[malc <av1474@comtv.ru>]

Breaks (at least) SB16. Apparently doesn't do what commit message says
it does.

This reverts commit 22bfa75eafc21522afbb265091faa9cc0649e9fb.
---
 async.c       |   23 ++++++++++++++++-------
 oslib-posix.c |   31 +++++++++++++++++++++++++++++++
 qemu-aio.h    |    1 +
 qemu-common.h |    1 +
 4 files changed, 49 insertions(+), 7 deletions(-)

diff --git a/async.c b/async.c
index 04f9dcb..564526f 100644
--- a/async.c
+++ b/async.c
@@ -117,20 +117,16 @@ void qemu_bh_delete(QEMUBH *bh)
     bh->deleted = 1;
 }
 
-static gboolean
-aio_ctx_prepare(GSource *source, gint    *timeout)
+void aio_bh_update_timeout(AioContext *ctx, uint32_t *timeout)
 {
-    AioContext *ctx = (AioContext *) source;
     QEMUBH *bh;
-    bool scheduled = false;
 
     for (bh = ctx->first_bh; bh; bh = bh->next) {
         if (!bh->deleted && bh->scheduled) {
-            scheduled = true;
             if (bh->idle) {
                 /* idle bottom halves will be polled at least
                  * every 10ms */
-                *timeout = 10;
+                *timeout = MIN(10, *timeout);
             } else {
                 /* non-idle bottom halves will be executed
                  * immediately */
@@ -139,8 +135,21 @@ aio_ctx_prepare(GSource *source, gint    *timeout)
             }
         }
     }
+}
+
+static gboolean
+aio_ctx_prepare(GSource *source, gint    *timeout)
+{
+    AioContext *ctx = (AioContext *) source;
+    uint32_t wait = -1;
+    aio_bh_update_timeout(ctx, &wait);
+
+    if (wait != -1) {
+        *timeout = MIN(*timeout, wait);
+        return wait == 0;
+    }
 
-    return scheduled;
+    return false;
 }
 
 static gboolean
diff --git a/oslib-posix.c b/oslib-posix.c
index 9db9c3d..dbeb627 100644
--- a/oslib-posix.c
+++ b/oslib-posix.c
@@ -61,6 +61,9 @@ static int running_on_valgrind = -1;
 #ifdef CONFIG_LINUX
 #include <sys/syscall.h>
 #endif
+#ifdef CONFIG_EVENTFD
+#include <sys/eventfd.h>
+#endif
 
 int qemu_get_thread_id(void)
 {
@@ -180,6 +183,34 @@ int qemu_pipe(int pipefd[2])
     return ret;
 }
 
+/*
+ * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
+ */
+int qemu_eventfd(int fds[2])
+{
+#ifdef CONFIG_EVENTFD
+    int ret;
+
+    ret = eventfd(0, 0);
+    if (ret >= 0) {
+        fds[0] = ret;
+        fds[1] = dup(ret);
+        if (fds[1] == -1) {
+            close(ret);
+            return -1;
+        }
+        qemu_set_cloexec(ret);
+        qemu_set_cloexec(fds[1]);
+        return 0;
+    }
+    if (errno != ENOSYS) {
+        return -1;
+    }
+#endif
+
+    return qemu_pipe(fds);
+}
+
 int qemu_utimens(const char *path, const struct timespec *times)
 {
     struct timeval tv[2], tv_now;
diff --git a/qemu-aio.h b/qemu-aio.h
index 1b7eb6e..2354617 100644
--- a/qemu-aio.h
+++ b/qemu-aio.h
@@ -125,6 +125,7 @@ void aio_notify(AioContext *ctx);
  * These are internal functions used by the QEMU main loop.
  */
 int aio_bh_poll(AioContext *ctx);
+void aio_bh_update_timeout(AioContext *ctx, uint32_t *timeout);
 
 /**
  * qemu_bh_schedule: Schedule a bottom half.
diff --git a/qemu-common.h b/qemu-common.h
index ac9985c..5059a97 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -218,6 +218,7 @@ ssize_t qemu_recv_full(int fd, void *buf, size_t count, int flags)
     QEMU_WARN_UNUSED_RESULT;
 
 #ifndef _WIN32
+int qemu_eventfd(int pipefd[2]);
 int qemu_pipe(int pipefd[2]);
 #endif
 
-- 
1.7.8.1.385.gec330