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Subject[RFC PATCH 11/60] hyper_dmabuf: check stack before unmapping/detaching shadow DMA_BUF
Date
Make sure list of mapping/attaching activities on impoter VM is not
empty before doing unmapping/detaching shadow DMA BUF for indirect
synchronization.

Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
.../xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c | 68 +++++++++++++++++-----
1 file changed, 53 insertions(+), 15 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
index 6ba932f..fa2fa11 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
@@ -11,6 +11,21 @@

extern struct hyper_dmabuf_private hyper_dmabuf_private;

+/* Whenever importer does dma operations from remote domain,
+ * a notification is sent to the exporter so that exporter
+ * issues equivalent dma operation on the original dma buf
+ * for indirect synchronization via shadow operations.
+ *
+ * All ptrs and references (e.g struct sg_table*,
+ * struct dma_buf_attachment) created via these operations on
+ * exporter's side are kept in stack (implemented as circular
+ * linked-lists) separately so that those can be re-referenced
+ * later when unmapping operations are invoked to free those.
+ *
+ * The very first element on the bottom of each stack holds
+ * are what is created when initial exporting is issued so it
+ * should not be modified or released by this fuction.
+ */
int hyper_dmabuf_remote_sync(int id, int ops)
{
struct hyper_dmabuf_sgt_info *sgt_info;
@@ -33,7 +48,7 @@ int hyper_dmabuf_remote_sync(int id, int ops)
attachl = kcalloc(1, sizeof(*attachl), GFP_KERNEL);

attachl->attach = dma_buf_attach(sgt_info->dma_buf,
- hyper_dmabuf_private.device);
+ hyper_dmabuf_private.device);

if (!attachl->attach) {
kfree(attachl);
@@ -45,22 +60,31 @@ int hyper_dmabuf_remote_sync(int id, int ops)
break;

case HYPER_DMABUF_OPS_DETACH:
- attachl = list_first_entry(&sgt_info->active_attached->list,
- struct attachment_list, list);
-
- if (!attachl) {
+ if (list_empty(&sgt_info->active_attached->list)) {
printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_DETACH\n");
+ printk("no more dmabuf attachment left to be detached\n");
return -EINVAL;
}
+
+ attachl = list_first_entry(&sgt_info->active_attached->list,
+ struct attachment_list, list);
+
dma_buf_detach(sgt_info->dma_buf, attachl->attach);
list_del(&attachl->list);
kfree(attachl);
break;

case HYPER_DMABUF_OPS_MAP:
- sgtl = kcalloc(1, sizeof(*sgtl), GFP_KERNEL);
+ if (list_empty(&sgt_info->active_attached->list)) {
+ printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_MAP\n");
+ printk("no more dmabuf attachment left to be detached\n");
+ return -EINVAL;
+ }
+
attachl = list_first_entry(&sgt_info->active_attached->list,
- struct attachment_list, list);
+ struct attachment_list, list);
+
+ sgtl = kcalloc(1, sizeof(*sgtl), GFP_KERNEL);
sgtl->sgt = dma_buf_map_attachment(attachl->attach, DMA_BIDIRECTIONAL);
if (!sgtl->sgt) {
kfree(sgtl);
@@ -71,17 +95,20 @@ int hyper_dmabuf_remote_sync(int id, int ops)
break;

case HYPER_DMABUF_OPS_UNMAP:
- attachl = list_first_entry(&sgt_info->active_attached->list,
- struct attachment_list, list);
- sgtl = list_first_entry(&sgt_info->active_sgts->list,
- struct sgt_list, list);
- if (!attachl || !sgtl) {
+ if (list_empty(&sgt_info->active_sgts->list) ||
+ list_empty(&sgt_info->active_attached->list)) {
printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_UNMAP\n");
+ printk("no more SGT or attachment left to be freed\n");
return -EINVAL;
}

+ attachl = list_first_entry(&sgt_info->active_attached->list,
+ struct attachment_list, list);
+ sgtl = list_first_entry(&sgt_info->active_sgts->list,
+ struct sgt_list, list);
+
dma_buf_unmap_attachment(attachl->attach, sgtl->sgt,
- DMA_BIDIRECTIONAL);
+ DMA_BIDIRECTIONAL);
list_del(&sgtl->list);
kfree(sgtl);
break;
@@ -129,9 +156,15 @@ int hyper_dmabuf_remote_sync(int id, int ops)

case HYPER_DMABUF_OPS_KUNMAP_ATOMIC:
case HYPER_DMABUF_OPS_KUNMAP:
+ if (list_empty(&sgt_info->va_kmapped->list)) {
+ printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_KUNMAP(_ATOMIC)\n");
+ printk("no more dmabuf VA to be freed\n");
+ return -EINVAL;
+ }
+
va_kmapl = list_first_entry(&sgt_info->va_kmapped->list,
- struct kmap_vaddr_list, list);
- if (!va_kmapl || va_kmapl->vaddr == NULL) {
+ struct kmap_vaddr_list, list);
+ if (va_kmapl->vaddr == NULL) {
printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_KUNMAP(_ATOMIC)\n");
return -EINVAL;
}
@@ -167,6 +200,11 @@ int hyper_dmabuf_remote_sync(int id, int ops)
break;

case HYPER_DMABUF_OPS_VUNMAP:
+ if (list_empty(&sgt_info->va_vmapped->list)) {
+ printk("dmabuf remote sync::error while processing HYPER_DMABUF_OPS_VUNMAP\n");
+ printk("no more dmabuf VA to be freed\n");
+ return -EINVAL;
+ }
va_vmapl = list_first_entry(&sgt_info->va_vmapped->list,
struct vmap_vaddr_list, list);
if (!va_vmapl || va_vmapl->vaddr == NULL) {
--
2.7.4
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