[Qemu-devel] [V2 01/25] [virtio-9p] Add infrastructure to support glib threads and coroutines.

["Venkateswararao Jujjuri (JV)" <jvrao@linux.vnet.ibm.com>]

This patch is originally made by Arun Bharadwaj for glib support.
Later Harsh Prateek Bora added coroutines support.
This version implemented with suggestions from
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>.

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri "<jvrao@linux.vnet.ibm.com>
---
 Makefile.objs              |    2 +
 hw/9pfs/virtio-9p-coth.c   |   93 ++++++++++++++++++++++++++++++++++++++++++++
 hw/9pfs/virtio-9p-coth.h   |   58 +++++++++++++++++++++++++++
 hw/9pfs/virtio-9p-device.c |    7 ++-
 4 files changed, 158 insertions(+), 2 deletions(-)
 create mode 100644 hw/9pfs/virtio-9p-coth.c
 create mode 100644 hw/9pfs/virtio-9p-coth.h

diff --git a/Makefile.objs b/Makefile.objs
index 3873f10..96f6a24 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -297,8 +297,10 @@ hw-obj-$(CONFIG_SOUND) += $(sound-obj-y)
 9pfs-nested-$(CONFIG_VIRTFS) = virtio-9p.o virtio-9p-debug.o
 9pfs-nested-$(CONFIG_VIRTFS) +=  virtio-9p-local.o virtio-9p-xattr.o
 9pfs-nested-$(CONFIG_VIRTFS) +=   virtio-9p-xattr-user.o virtio-9p-posix-acl.o
+9pfs-nested-$(CONFIG_VIRTFS) += virtio-9p-coth.o
 
 hw-obj-$(CONFIG_REALLY_VIRTFS) += $(addprefix 9pfs/, $(9pfs-nested-y))
+$(addprefix 9pfs/, $(9pfs-nested-y)): QEMU_CFLAGS+=$(GLIB_CFLAGS)
 
 
 ######################################################################
diff --git a/hw/9pfs/virtio-9p-coth.c b/hw/9pfs/virtio-9p-coth.c
new file mode 100644
index 0000000..e61b656
--- /dev/null
+++ b/hw/9pfs/virtio-9p-coth.c
@@ -0,0 +1,93 @@
+/*
+ * Virtio 9p backend
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
+ *  Venkateswararao Jujjuri(JV) <jvrao@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-char.h"
+#include "fsdev/qemu-fsdev.h"
+#include "qemu-thread.h"
+#include "qemu-coroutine.h"
+#include "virtio-9p-coth.h"
+
+/* v9fs glib thread pool */
+static V9fsThPool v9fs_pool;
+
+void co_run_in_worker_bh(void *opaque)
+{
+    Coroutine *co = opaque;
+    g_thread_pool_push(v9fs_pool.pool, co, NULL);
+}
+
+static void v9fs_qemu_process_req_done(void *arg)
+{
+    char byte;
+    ssize_t len;
+    Coroutine *co;
+
+    do {
+        len = read(v9fs_pool.rfd, &byte, sizeof(byte));
+    } while (len == -1 &&  errno == EINTR);
+
+    while ((co = g_async_queue_try_pop(v9fs_pool.completed)) != NULL) {
+        qemu_coroutine_enter(co, NULL);
+    }
+}
+
+static void v9fs_thread_routine(gpointer data, gpointer user_data)
+{
+    ssize_t len;
+    char byte = 0;
+    Coroutine *co = data;
+
+    qemu_coroutine_enter(co, NULL);
+
+    g_async_queue_push(v9fs_pool.completed, co);
+    do {
+        len = write(v9fs_pool.wfd, &byte, sizeof(byte));
+    } while (len == -1 && errno == EINTR);
+}
+
+int v9fs_init_worker_threads(void)
+{
+    int notifier_fds[2];
+    V9fsThPool *p = &v9fs_pool;
+
+    /* init thread system if not already initialized */
+    if (!g_thread_get_initialized()) {
+        g_thread_init(NULL);
+    }
+
+    if (qemu_pipe(notifier_fds) == -1) {
+        return -1;
+    }
+
+    p->pool = g_thread_pool_new(v9fs_thread_routine, p, -1, FALSE, NULL);
+    if (!p->pool) {
+        return -1;
+    }
+    p->completed = g_async_queue_new();
+    if (!p->completed) {
+        /*
+         * We are going to terminate.
+         * So don't worry about cleanup
+         */
+        return -1;
+    }
+    p->rfd = notifier_fds[0];
+    p->wfd = notifier_fds[1];
+
+    fcntl(p->rfd, F_SETFL, O_NONBLOCK);
+    fcntl(p->wfd, F_SETFL, O_NONBLOCK);
+
+    qemu_set_fd_handler(p->rfd, v9fs_qemu_process_req_done, NULL, NULL);
+    return 0;
+}
diff --git a/hw/9pfs/virtio-9p-coth.h b/hw/9pfs/virtio-9p-coth.h
new file mode 100644
index 0000000..8445d29
--- /dev/null
+++ b/hw/9pfs/virtio-9p-coth.h
@@ -0,0 +1,58 @@
+/*
+ * Virtio 9p backend
+ *
+ * Copyright IBM, Corp. 2010
+ *
+ * Authors:
+ *  Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
+ *  Venkateswararao Jujjuri(JV) <jvrao@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef _QEMU_VIRTIO_9P_COTH_H
+#define _QEMU_VIRTIO_9P_COTH_H
+
+#include "qemu-thread.h"
+#include "qemu-coroutine.h"
+#include <glib.h>
+
+typedef struct V9fsThPool {
+    int rfd;
+    int wfd;
+    GThreadPool *pool;
+    GAsyncQueue *completed;
+} V9fsThPool;
+
+/*
+ * we want to use bottom half because we want to make sure the below
+ * sequence of events.
+ *
+ *   1. Yield the coroutine in the QEMU thread.
+ *   2. Submit the coroutine to a worker thread.
+ *   3. Enter the coroutine in the worker thread.
+ * we cannot swap step 1 and 2, because that would imply worker thread
+ * can enter coroutine while step1 is still running
+ */
+#define v9fs_co_run_in_worker(code_block)                               \
+    do {                                                                \
+        QEMUBH *co_bh;                                                  \
+        co_bh = qemu_bh_new(co_run_in_worker_bh,                        \
+                            qemu_coroutine_self());                     \
+        qemu_bh_schedule(co_bh);                                        \
+        /*                                                              \
+         * yeild in qemu thread and re-enter back                       \
+         * in glib worker thread                                        \
+         */                                                             \
+        qemu_coroutine_yield();                                         \
+        qemu_bh_delete(co_bh);                                          \
+        code_block;                                                     \
+        /* re-enter back to qemu thread */                              \
+        qemu_coroutine_yield();                                         \
+    } while (0)
+
+extern void co_run_in_worker_bh(void *);
+extern int v9fs_init_worker_threads(void);
+#endif
diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index a2b6acc..7811103 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -18,6 +18,7 @@
 #include "virtio-9p.h"
 #include "fsdev/qemu-fsdev.h"
 #include "virtio-9p-xattr.h"
+#include "virtio-9p-coth.h"
 
 static uint32_t virtio_9p_get_features(VirtIODevice *vdev, uint32_t features)
 {
@@ -50,13 +51,11 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
     struct stat stat;
     FsTypeEntry *fse;
 
-
     s = (V9fsState *)virtio_common_init("virtio-9p",
                                     VIRTIO_ID_9P,
                                     sizeof(struct virtio_9p_config)+
                                     MAX_TAG_LEN,
                                     sizeof(V9fsState));
-
     /* initialize pdu allocator */
     QLIST_INIT(&s->free_list);
     for (i = 0; i < (MAX_REQ - 1); i++) {
@@ -132,6 +131,10 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf)
                         s->tag_len;
     s->vdev.get_config = virtio_9p_get_config;
 
+    if (v9fs_init_worker_threads() < 0) {
+        fprintf(stderr, "worker thread initialization failed\n");
+        exit(1);
+    }
     return &s->vdev;
 }
 
-- 
1.7.1