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Subject[RFC PATCH 15/60] hyper_dmabuf: reusing previously released hyper_dmabuf_id
Date
Now, released hyper_dmabuf_ids are stored in a stack -
(hyper_dmabuf_private.id_queue) for reuse. This is to prevent
overflow of ids for buffers. We also limit maximum number for
the id to 1000 for the stability and optimal performance.

Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
drivers/xen/hyper_dmabuf/Makefile | 1 +
drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c | 5 ++
drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.h | 6 ++
drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c | 76 ++++++++++++++++++++++
drivers/xen/hyper_dmabuf/hyper_dmabuf_id.h | 24 +++++++
drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c | 1 +
drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c | 15 ++---
.../xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c | 3 +
drivers/xen/hyper_dmabuf/hyper_dmabuf_struct.h | 9 ---
9 files changed, 120 insertions(+), 20 deletions(-)
create mode 100644 drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
create mode 100644 drivers/xen/hyper_dmabuf/hyper_dmabuf_id.h

diff --git a/drivers/xen/hyper_dmabuf/Makefile b/drivers/xen/hyper_dmabuf/Makefile
index 3459382..c9b8b7f 100644
--- a/drivers/xen/hyper_dmabuf/Makefile
+++ b/drivers/xen/hyper_dmabuf/Makefile
@@ -7,6 +7,7 @@ ifneq ($(KERNELRELEASE),)
hyper_dmabuf_list.o \
hyper_dmabuf_imp.o \
hyper_dmabuf_msg.o \
+ hyper_dmabuf_id.o \
hyper_dmabuf_remote_sync.o \
xen/hyper_dmabuf_xen_comm.o \
xen/hyper_dmabuf_xen_comm_list.o
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
index 5a7cfa5..66d6cb9 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
@@ -5,6 +5,7 @@
#include "hyper_dmabuf_drv.h"
#include "hyper_dmabuf_conf.h"
#include "hyper_dmabuf_list.h"
+#include "hyper_dmabuf_id.h"
#include "xen/hyper_dmabuf_xen_comm_list.h"
#include "xen/hyper_dmabuf_xen_comm.h"

@@ -67,6 +68,10 @@ static void hyper_dmabuf_drv_exit(void)
if (hyper_dmabuf_private.work_queue)
destroy_workqueue(hyper_dmabuf_private.work_queue);

+ /* destroy id_queue */
+ if (hyper_dmabuf_private.id_queue)
+ destroy_reusable_list();
+
hyper_dmabuf_destroy_data_dir();
printk( KERN_NOTICE "dma_buf-src_sink model: Exiting" );
unregister_device();
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.h b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.h
index ff883e1..37b0cc1 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.h
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.h
@@ -1,10 +1,16 @@
#ifndef __LINUX_PUBLIC_HYPER_DMABUF_DRV_H__
#define __LINUX_PUBLIC_HYPER_DMABUF_DRV_H__

+struct list_reusable_id {
+ int id;
+ struct list_head list;
+};
+
struct hyper_dmabuf_private {
struct device *device;
int domid;
struct workqueue_struct *work_queue;
+ struct list_reusable_id *id_queue;
};

typedef int (*hyper_dmabuf_ioctl_t)(void *data);
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
new file mode 100644
index 0000000..7bbb179
--- /dev/null
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.c
@@ -0,0 +1,76 @@
+#include <linux/list.h>
+#include <linux/slab.h>
+#include "hyper_dmabuf_drv.h"
+#include "hyper_dmabuf_id.h"
+
+extern struct hyper_dmabuf_private hyper_dmabuf_private;
+
+void store_reusable_id(int id)
+{
+ struct list_reusable_id *reusable_head = hyper_dmabuf_private.id_queue;
+ struct list_reusable_id *new_reusable;
+
+ new_reusable = kmalloc(sizeof(*new_reusable), GFP_KERNEL);
+ new_reusable->id = id;
+
+ list_add(&new_reusable->list, &reusable_head->list);
+}
+
+static int retrieve_reusable_id(void)
+{
+ struct list_reusable_id *reusable_head = hyper_dmabuf_private.id_queue;
+
+ /* check there is reusable id */
+ if (!list_empty(&reusable_head->list)) {
+ reusable_head = list_first_entry(&reusable_head->list,
+ struct list_reusable_id,
+ list);
+
+ list_del(&reusable_head->list);
+ return reusable_head->id;
+ }
+
+ return -1;
+}
+
+void destroy_reusable_list(void)
+{
+ struct list_reusable_id *reusable_head = hyper_dmabuf_private.id_queue;
+ struct list_reusable_id *temp_head;
+
+ if (reusable_head) {
+ /* freeing mem space all reusable ids in the stack */
+ while (!list_empty(&reusable_head->list)) {
+ temp_head = list_first_entry(&reusable_head->list,
+ struct list_reusable_id,
+ list);
+ list_del(&temp_head->list);
+ kfree(temp_head);
+ }
+
+ /* freeing head */
+ kfree(reusable_head);
+ }
+}
+
+int hyper_dmabuf_get_id(void)
+{
+ static int id = 0;
+ struct list_reusable_id *reusable_head;
+ int ret;
+
+ /* first cla to hyper_dmabuf_get_id */
+ if (id == 0) {
+ reusable_head = kmalloc(sizeof(*reusable_head), GFP_KERNEL);
+ reusable_head->id = -1; /* list head have invalid id */
+ INIT_LIST_HEAD(&reusable_head->list);
+ hyper_dmabuf_private.id_queue = reusable_head;
+ }
+
+ ret = retrieve_reusable_id();
+
+ if (ret < 0 && id < HYPER_DMABUF_ID_MAX)
+ return HYPER_DMABUF_ID_CREATE(hyper_dmabuf_private.domid, id++);
+
+ return ret;
+}
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.h b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.h
new file mode 100644
index 0000000..2c8daf3
--- /dev/null
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_id.h
@@ -0,0 +1,24 @@
+#ifndef __HYPER_DMABUF_ID_H__
+#define __HYPER_DMABUF_ID_H__
+
+/* Importer combine source domain id with given hyper_dmabuf_id
+ * to make it unique in case there are multiple exporters */
+
+#define HYPER_DMABUF_ID_CREATE(domid, id) \
+ ((((domid) & 0xFF) << 24) | ((id) & 0xFFFFFF))
+
+#define HYPER_DMABUF_DOM_ID(id) \
+ (((id) >> 24) & 0xFF)
+
+/* currently maximum number of buffers shared
+ * at any given moment is limited to 1000
+ */
+#define HYPER_DMABUF_ID_MAX 1000
+
+void store_reusable_id(int id);
+
+void destroy_reusable_list(void);
+
+int hyper_dmabuf_get_id(void);
+
+#endif /*__HYPER_DMABUF_ID_H*/
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
index fa445e5..b109138 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
@@ -7,6 +7,7 @@
#include <asm/xen/page.h>
#include "hyper_dmabuf_struct.h"
#include "hyper_dmabuf_imp.h"
+#include "hyper_dmabuf_id.h"
#include "xen/hyper_dmabuf_xen_comm.h"
#include "hyper_dmabuf_msg.h"
#include "hyper_dmabuf_list.h"
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
index e334b77..5c6d9c8 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_ioctl.c
@@ -11,6 +11,7 @@
#include "hyper_dmabuf_imp.h"
#include "hyper_dmabuf_list.h"
#include "hyper_dmabuf_drv.h"
+#include "hyper_dmabuf_id.h"
#include "hyper_dmabuf_query.h"
#include "xen/hyper_dmabuf_xen_comm.h"
#include "xen/hyper_dmabuf_xen_comm_list.h"
@@ -18,16 +19,6 @@

extern struct hyper_dmabuf_private hyper_dmabuf_private;

-static uint32_t hyper_dmabuf_id_gen(void) {
- /* TODO: add proper implementation */
- static uint32_t id = 1000;
- static int32_t domid = -1;
- if (domid == -1) {
- domid = hyper_dmabuf_get_domid();
- }
- return HYPER_DMABUF_ID_IMPORTER(domid, id++);
-}
-
static int hyper_dmabuf_exporter_ring_setup(void *data)
{
struct ioctl_hyper_dmabuf_exporter_ring_setup *ring_attr;
@@ -133,7 +124,7 @@ static int hyper_dmabuf_export_remote(void *data)

sgt_info = kmalloc(sizeof(*sgt_info), GFP_KERNEL);

- sgt_info->hyper_dmabuf_id = hyper_dmabuf_id_gen();
+ sgt_info->hyper_dmabuf_id = hyper_dmabuf_get_id();
/* TODO: We might need to consider using port number on event channel? */
sgt_info->hyper_dmabuf_rdomain = export_remote_attr->remote_domain;
sgt_info->dma_buf = dma_buf;
@@ -334,6 +325,8 @@ static int hyper_dmabuf_unexport(void *data)
hyper_dmabuf_cleanup_sgt_info(sgt_info, false);
hyper_dmabuf_remove_exported(unexport_attr->hyper_dmabuf_id);
kfree(sgt_info);
+ /* register hyper_dmabuf_id to the list for reuse */
+ store_reusable_id(unexport_attr->hyper_dmabuf_id);
}

return ret;
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
index 5017b17..c5950e0 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_remote_sync.c
@@ -6,6 +6,7 @@
#include "hyper_dmabuf_struct.h"
#include "hyper_dmabuf_list.h"
#include "hyper_dmabuf_drv.h"
+#include "hyper_dmabuf_id.h"
#include "xen/hyper_dmabuf_xen_comm.h"
#include "hyper_dmabuf_msg.h"
#include "hyper_dmabuf_imp.h"
@@ -124,6 +125,8 @@ int hyper_dmabuf_remote_sync(int id, int ops)
hyper_dmabuf_cleanup_sgt_info(sgt_info, false);
hyper_dmabuf_remove_exported(id);
kfree(sgt_info);
+ /* store hyper_dmabuf_id in the list for reuse */
+ store_reusable_id(id);
}

break;
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_struct.h b/drivers/xen/hyper_dmabuf/hyper_dmabuf_struct.h
index 92e06ff..b52f958 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_struct.h
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_struct.h
@@ -3,15 +3,6 @@

#include <xen/interface/grant_table.h>

-/* Importer combine source domain id with given hyper_dmabuf_id
- * to make it unique in case there are multiple exporters */
-
-#define HYPER_DMABUF_ID_IMPORTER(domid, id) \
- ((((domid) & 0xFF) << 24) | ((id) & 0xFFFFFF))
-
-#define HYPER_DMABUF_DOM_ID(id) \
- (((id) >> 24) & 0xFF)
-
/* each grant_ref_t is 4 bytes, so total 4096 grant_ref_t can be
* in this block meaning we can share 4KB*4096 = 16MB of buffer
* (needs to be increased for large buffer use-cases such as 4K
--
2.7.4
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