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

[Dongwon Kim <dongwon.kim@xxxxxxxxx>]

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


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