[PATCH 3/6] kvm: qemu: add qemu_eventfd_write() and qemu_eventfd_read()

[Mark McLoughlin <markmc@redhat.com>]

Split out code for common eventfd operations to avoid
re-implementation.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
---
 qemu/compatfd.c |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 qemu/compatfd.h |    2 ++
 qemu/qemu-kvm.c |   42 ++++--------------------------------------
 3 files changed, 54 insertions(+), 38 deletions(-)

diff --git a/qemu/compatfd.c b/qemu/compatfd.c
index 36e37e5..7e3e7f7 100644
--- a/qemu/compatfd.c
+++ b/qemu/compatfd.c
@@ -129,3 +129,51 @@ int qemu_eventfd(int *fds)
 
     return pipe(fds);
 }
+
+int qemu_eventfd_write(int eventfd, uint64_t value)
+{
+    char buffer[8];
+    size_t offset = 0;
+
+    memcpy(buffer, &value, sizeof(value));
+
+    while (offset < 8) {
+	ssize_t len;
+
+	len = write(eventfd, buffer + offset, 8 - offset);
+	if (len == -1 && errno == EINTR)
+	    continue;
+
+	if (len <= 0)
+	    break;
+
+	offset += len;
+    }
+
+    return offset == 8 ? 0 : -1;
+}
+
+uint64_t qemu_eventfd_read(int eventfd)
+{
+    char buffer[8];
+    size_t offset = 0;
+    uint64_t value = 0;
+
+    while (offset < 8) {
+	ssize_t len;
+
+	len = read(eventfd, buffer + offset, 8 - offset);
+	if (len == -1 && errno == EINTR)
+	    continue;
+
+	if (len <= 0)
+	    break;
+
+	offset += len;
+    }
+
+    if (offset == 8)
+        memcpy(&value, buffer, sizeof(value));
+
+    return value;
+}
diff --git a/qemu/compatfd.h b/qemu/compatfd.h
index 55a111a..b2792e6 100644
--- a/qemu/compatfd.h
+++ b/qemu/compatfd.h
@@ -24,5 +24,7 @@ struct qemu_signalfd_siginfo {
 int qemu_signalfd(const sigset_t *mask);
 
 int qemu_eventfd(int *fds);
+int qemu_eventfd_write(int eventfd, uint64_t value);
+uint64_t qemu_eventfd_read(int eventfd);
 
 #endif
diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
index c5f3f29..70c6802 100644
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -485,30 +485,11 @@ int kvm_init_ap(void)
 
 void qemu_kvm_notify_work(void)
 {
-    uint64_t value = 1;
-    char buffer[8];
-    size_t offset = 0;
-
     if (io_thread_fd == -1)
-	return;
-
-    memcpy(buffer, &value, sizeof(value));
-
-    while (offset < 8) {
-	ssize_t len;
-
-	len = write(io_thread_fd, buffer + offset, 8 - offset);
-	if (len == -1 && errno == EINTR)
-	    continue;
-
-	if (len <= 0)
-	    break;
-
-	offset += len;
-    }
+        return;
 
-    if (offset != 8)
-	fprintf(stderr, "failed to notify io thread\n");
+    if (qemu_eventfd_write(io_thread_fd, 1) != 0)
+        fprintf(stderr, "failed to notify io thread\n");
 }
 
 /* If we have signalfd, we mask out the signals we want to handle and then
@@ -546,22 +527,7 @@ static void sigfd_handler(void *opaque)
 /* Used to break IO thread out of select */
 static void io_thread_wakeup(void *opaque)
 {
-    int fd = (unsigned long)opaque;
-    char buffer[8];
-    size_t offset = 0;
-
-    while (offset < 8) {
-	ssize_t len;
-
-	len = read(fd, buffer + offset, 8 - offset);
-	if (len == -1 && errno == EINTR)
-	    continue;
-
-	if (len <= 0)
-	    break;
-
-	offset += len;
-    }
+    qemu_eventfd_read((unsigned long)opaque);
 }
 
 int kvm_main_loop(void)
-- 
1.5.4.3