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Subject[RFC PATCH 53/60] hyper_dmabuf: define fastpath_export for exporting existing buffer
Date
To make hyper_dmabuf_export_remote_ioctl more compact and readable,
a new function call, 'fastpath_export' is created to replace a routine
in hyper_dmabuf_export_remote_ioctl for the case requested buffer for
exporting is already in the LIST (exported previously).

Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c | 153 +++++++++++++++-----------
1 file changed, 87 insertions(+), 66 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
index b40cf89..d11f609 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
@@ -122,6 +122,82 @@ static int send_export_msg(struct exported_sgt_info *exported,
return ret;
}

+/* Fast path exporting routine in case same buffer is already exported.
+ * In this function, we skip normal exporting process and just update
+ * private data on both VMs (importer and exporter)
+ *
+ * return '1' if reexport is needed, return '0' if succeeds, return
+ * Kernel error code if something goes wrong
+ */
+static int fastpath_export(hyper_dmabuf_id_t hid, int sz_priv, char *priv)
+{
+ int reexport = 1;
+ int ret = 0;
+ struct exported_sgt_info *exported;
+
+ exported = hyper_dmabuf_find_exported(hid);
+
+ if (!exported)
+ return reexport;
+
+ if (exported->valid == false)
+ return reexport;
+
+ /*
+ * Check if unexport is already scheduled for that buffer,
+ * if so try to cancel it. If that will fail, buffer needs
+ * to be reexport once again.
+ */
+ if (exported->unexport_sched) {
+ if (!cancel_delayed_work_sync(&exported->unexport))
+ return reexport;
+
+ exported->unexport_sched = false;
+ }
+
+ /* if there's any change in size of private data.
+ * we reallocate space for private data with new size
+ */
+ if (sz_priv != exported->sz_priv) {
+ kfree(exported->priv);
+
+ /* truncating size */
+ if (sz_priv > MAX_SIZE_PRIV_DATA)
+ exported->sz_priv = MAX_SIZE_PRIV_DATA;
+ else
+ exported->sz_priv = sz_priv;
+
+ exported->priv = kcalloc(1, exported->sz_priv,
+ GFP_KERNEL);
+
+ if (!exported->priv) {
+ hyper_dmabuf_remove_exported(exported->hid);
+ hyper_dmabuf_cleanup_sgt_info(exported, true);
+ kfree(exported);
+ return -ENOMEM;
+ }
+ }
+
+ /* update private data in sgt_info with new ones */
+ ret = copy_from_user(exported->priv, priv, exported->sz_priv);
+ if (ret) {
+ dev_err(hy_drv_priv->dev,
+ "Failed to load a new private data\n");
+ ret = -EINVAL;
+ } else {
+ /* send an export msg for updating priv in importer */
+ ret = send_export_msg(exported, NULL);
+
+ if (ret < 0) {
+ dev_err(hy_drv_priv->dev,
+ "Failed to send a new private data\n");
+ ret = -EBUSY;
+ }
+ }
+
+ return ret;
+}
+
static int hyper_dmabuf_export_remote_ioctl(struct file *filp, void *data)
{
struct ioctl_hyper_dmabuf_export_remote *export_remote_attr =
@@ -153,79 +229,24 @@ static int hyper_dmabuf_export_remote_ioctl(struct file *filp, void *data)
*/
hid = hyper_dmabuf_find_hid_exported(dma_buf,
export_remote_attr->remote_domain);
- if (hid.id != -1) {
- exported = hyper_dmabuf_find_exported(hid);

- if (!exported)
- goto reexport;
-
- if (exported->valid == false)
- goto reexport;
+ if (hid.id != -1) {
+ ret = fastpath_export(hid, export_remote_attr->sz_priv,
+ export_remote_attr->priv);

- /*
- * Check if unexport is already scheduled for that buffer,
- * if so try to cancel it. If that will fail, buffer needs
- * to be reexport once again.
+ /* return if fastpath_export succeeds or
+ * gets some fatal error
*/
- if (exported->unexport_sched) {
- if (!cancel_delayed_work_sync(&exported->unexport)) {
- dma_buf_put(dma_buf);
- goto reexport;
- }
- exported->unexport_sched = false;
+ if (ret <= 0) {
+ dma_buf_put(dma_buf);
+ export_remote_attr->hid = hid;
+ return ret;
}
-
- /* if there's any change in size of private data.
- * we reallocate space for private data with new size
- */
- if (export_remote_attr->sz_priv != exported->sz_priv) {
- kfree(exported->priv);
-
- /* truncating size */
- if (export_remote_attr->sz_priv > MAX_SIZE_PRIV_DATA)
- exported->sz_priv = MAX_SIZE_PRIV_DATA;
- else
- exported->sz_priv = export_remote_attr->sz_priv;
-
- exported->priv = kcalloc(1, exported->sz_priv,
- GFP_KERNEL);
-
- if (!exported->priv) {
- hyper_dmabuf_remove_exported(exported->hid);
- hyper_dmabuf_cleanup_sgt_info(exported, true);
- kfree(exported);
- dma_buf_put(dma_buf);
- return -ENOMEM;
- }
- }
-
- /* update private data in sgt_info with new ones */
- ret = copy_from_user(exported->priv, export_remote_attr->priv,
- exported->sz_priv);
- if (ret) {
- dev_err(hy_drv_priv->dev,
- "Failed to load a new private data\n");
- ret = -EINVAL;
- } else {
- /* send an export msg for updating priv in importer */
- ret = send_export_msg(exported, NULL);
-
- if (ret < 0) {
- dev_err(hy_drv_priv->dev,
- "Failed to send a new private data\n");
- ret = -EBUSY;
- }
- }
-
- dma_buf_put(dma_buf);
- export_remote_attr->hid = hid;
- return ret;
}

-reexport:
attachment = dma_buf_attach(dma_buf, hy_drv_priv->dev);
if (IS_ERR(attachment)) {
- dev_err(hy_drv_priv->dev, "Cannot get attachment\n");
+ dev_err(hy_drv_priv->dev, "cannot get attachment\n");
ret = PTR_ERR(attachment);
goto fail_attach;
}
@@ -233,7 +254,7 @@ static int hyper_dmabuf_export_remote_ioctl(struct file *filp, void *data)
sgt = dma_buf_map_attachment(attachment, DMA_BIDIRECTIONAL);

if (IS_ERR(sgt)) {
- dev_err(hy_drv_priv->dev, "Cannot map attachment\n");
+ dev_err(hy_drv_priv->dev, "cannot map attachment\n");
ret = PTR_ERR(sgt);
goto fail_map_attachment;
}
--
2.7.4
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