[RFC PATCH 05/60] hyper_dmabuf: skip creating a comm ch if exist for the VM

[Dongwon Kim]

hyper_dmabuf_importer_ring_setup creates new channel only if
there is no existing downstream communication channel previously
created for the exporter VM.

Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
 drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c   | 13 +++++++------
 drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
index 3b40ec0..6b16e37 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
@@ -827,12 +827,11 @@ static const struct dma_buf_ops hyper_dmabuf_ops = {
 int hyper_dmabuf_export_fd(struct hyper_dmabuf_imported_sgt_info *dinfo, int flags)
 {
 	int fd;
-
 	struct dma_buf* dmabuf;
 
-/* call hyper_dmabuf_export_dmabuf and create and bind a handle for it
- * then release */
-
+	/* call hyper_dmabuf_export_dmabuf and create
+	 * and bind a handle for it then release
+	 */
 	dmabuf = hyper_dmabuf_export_dma_buf(dinfo);
 
 	fd = dma_buf_fd(dmabuf, flags);
@@ -845,9 +844,11 @@ struct dma_buf* hyper_dmabuf_export_dma_buf(struct hyper_dmabuf_imported_sgt_inf
 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 
 	exp_info.ops = &hyper_dmabuf_ops;
-	exp_info.size = dinfo->sgt->nents * PAGE_SIZE; /* multiple of PAGE_SIZE, not considering offset */
+
+	/* multiple of PAGE_SIZE, not considering offset */
+	exp_info.size = dinfo->sgt->nents * PAGE_SIZE;
 	exp_info.flags = /* not sure about flag */0;
 	exp_info.priv = dinfo;
 
 	return dma_buf_export(&exp_info);
-};
+}
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
index 665cada..90e0c65 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
@@ -12,6 +12,7 @@
 #include "hyper_dmabuf_drv.h"
 #include "hyper_dmabuf_query.h"
 #include "xen/hyper_dmabuf_xen_comm.h"
+#include "xen/hyper_dmabuf_xen_comm_list.h"
 #include "hyper_dmabuf_msg.h"
 
 struct hyper_dmabuf_private {
@@ -31,6 +32,7 @@ static uint32_t hyper_dmabuf_id_gen(void) {
 static int hyper_dmabuf_exporter_ring_setup(void *data)
 {
 	struct ioctl_hyper_dmabuf_exporter_ring_setup *ring_attr;
+	struct hyper_dmabuf_ring_info_export *ring_info;
 	int ret = 0;
 
 	if (!data) {
@@ -39,6 +41,15 @@ static int hyper_dmabuf_exporter_ring_setup(void *data)
 	}
 	ring_attr = (struct ioctl_hyper_dmabuf_exporter_ring_setup *)data;
 
+	/* check if the ring ch already exists */
+	ring_info = hyper_dmabuf_find_exporter_ring(ring_attr->remote_domain);
+
+	if (ring_info) {
+		printk("(exporter's) ring ch to domid = %d already exist\ngref = %d, port = %d\n",
+			ring_info->rdomain, ring_info->gref_ring, ring_info->port);
+		return 0;
+	}
+
 	ret = hyper_dmabuf_exporter_ringbuf_init(ring_attr->remote_domain,
 						&ring_attr->ring_refid,
 						&ring_attr->port);
@@ -49,6 +60,7 @@ static int hyper_dmabuf_exporter_ring_setup(void *data)
 static int hyper_dmabuf_importer_ring_setup(void *data)
 {
 	struct ioctl_hyper_dmabuf_importer_ring_setup *setup_imp_ring_attr;
+	struct hyper_dmabuf_ring_info_import *ring_info;
 	int ret = 0;
 
 	if (!data) {
@@ -58,6 +70,14 @@ static int hyper_dmabuf_importer_ring_setup(void *data)
 
 	setup_imp_ring_attr = (struct ioctl_hyper_dmabuf_importer_ring_setup *)data;
 
+	/* check if the ring ch already exist */
+	ring_info = hyper_dmabuf_find_importer_ring(setup_imp_ring_attr->source_domain);
+
+	if (ring_info) {
+		printk("(importer's) ring ch to domid = %d already exist\n", ring_info->sdomain);
+		return 0;
+	}
+
 	/* user need to provide a port number and ref # for the page used as ring buffer */
 	ret = hyper_dmabuf_importer_ringbuf_init(setup_imp_ring_attr->source_domain,
 						 setup_imp_ring_attr->ring_refid,
-- 
2.7.4