use eventfd for iothread

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/osdep.c b/osdep.c
index 9059f019e7..9e4b17bd48 100644
--- a/osdep.c
+++ b/osdep.c
@@ -37,6 +37,10 @@
 #include <sys/statvfs.h>
 #endif
 
+#ifdef CONFIG_EVENTFD
+#include <sys/eventfd.h>
+#endif
+
 #ifdef _WIN32
 #include <windows.h>
 #elif defined(CONFIG_BSD)
@@ -281,6 +285,34 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 
 #ifndef _WIN32
 /*
+ * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
+ */
+int qemu_eventfd(int fds[2])
+{
+    int ret;
+
+#ifdef CONFIG_EVENTFD
+    ret = eventfd(0, 0);
+    if (ret >= 0) {
+        fds[0] = ret;
+        qemu_set_cloexec(ret);
+        if ((fds[1] = dup(ret)) == -1) {
+            close(ret);
+            return -1;
+        }
+        qemu_set_cloexec(fds[1]);
+        return 0;
+    }
+
+    if (errno != ENOSYS) {
+        return -1;
+    }
+#endif
+
+    return qemu_pipe(fds);
+}
+
+/*
  * Creates a pipe with FD_CLOEXEC set on both file descriptors
  */
 int qemu_pipe(int pipefd[2])