[RFC PATCH 21/60] hyper_dmabuf: exposing drv information using sysfs

[Dongwon Kim]

From: MichaÅ Janiszewski <michal1x.janiszewski@xxxxxxxxx>

This adds two entries in SYSFS with information about imported
and exported entries. The information exposed contains details
about number of pages, whether a buffer is valid or not, and
importer/exporter count.

Sysfs for hyper_dmabuf can be enabled by setting a new config
option, "CONFIG_HYPER_DMABUF_SYSFS" to 'yes'.

Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
 drivers/xen/hyper_dmabuf/Kconfig             |  7 +++
 drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c  | 12 ++++-
 drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c  |  2 +-
 drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c | 74 ++++++++++++++++++++++++++++
 drivers/xen/hyper_dmabuf/hyper_dmabuf_list.h |  3 ++
 5 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/hyper_dmabuf/Kconfig b/drivers/xen/hyper_dmabuf/Kconfig
index 75e1f96..56633a2 100644
--- a/drivers/xen/hyper_dmabuf/Kconfig
+++ b/drivers/xen/hyper_dmabuf/Kconfig
@@ -11,4 +11,11 @@ config HYPER_DMABUF_XEN
 	help
 	  Configuring hyper_dmabuf driver for XEN hypervisor
 
+config HYPER_DMABUF_SYSFS
+	bool "Enable sysfs information about hyper DMA buffers"
+	default y
+	help
+	  Expose information about imported and exported buffers using
+	  hyper_dmabuf driver
+
 endmenu
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
index 9d99769..3fc30e6 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_drv.c
@@ -22,7 +22,7 @@ int unregister_device(void);
 struct hyper_dmabuf_private hyper_dmabuf_private;
 
 /*===============================================================================================*/
-static int hyper_dmabuf_drv_init(void)
+static int __init hyper_dmabuf_drv_init(void)
 {
 	int ret = 0;
 
@@ -51,10 +51,16 @@ static int hyper_dmabuf_drv_init(void)
 	}
 
 	ret = hyper_dmabuf_private.backend_ops->init_comm_env();
+	if (ret < 0) {
+		return -EINVAL;
+	}
 
+#ifdef CONFIG_HYPER_DMABUF_SYSFS
+	ret = hyper_dmabuf_register_sysfs(hyper_dmabuf_private.device);
 	if (ret < 0) {
 		return -EINVAL;
 	}
+#endif
 
 	/* interrupt for comm should be registered here: */
 	return ret;
@@ -63,6 +69,10 @@ static int hyper_dmabuf_drv_init(void)
 /*-----------------------------------------------------------------------------------------------*/
 static void hyper_dmabuf_drv_exit(void)
 {
+#ifdef CONFIG_HYPER_DMABUF_SYSFS
+	hyper_dmabuf_unregister_sysfs(hyper_dmabuf_private.device);
+#endif
+
 	/* hash tables for export/import entries and ring_infos */
 	hyper_dmabuf_table_destroy();
 
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
index 9b05063..924710f 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_imp.c
@@ -24,7 +24,7 @@ int dmabuf_refcount(struct dma_buf *dma_buf)
 	return -1;
 }
 
-/* return total number of pages referecned by a sgt
+/* return total number of pages referenced by a sgt
  * for pre-calculation of # of pages behind a given sgt
  */
 static int hyper_dmabuf_get_num_pgs(struct sg_table *sgt)
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
index 18731de..1d224c4 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.c
@@ -11,6 +11,80 @@
 DECLARE_HASHTABLE(hyper_dmabuf_hash_imported, MAX_ENTRY_IMPORTED);
 DECLARE_HASHTABLE(hyper_dmabuf_hash_exported, MAX_ENTRY_EXPORTED);
 
+#ifdef CONFIG_HYPER_DMABUF_SYSFS
+static ssize_t hyper_dmabuf_imported_show(struct device *drv, struct device_attribute *attr, char *buf)
+{
+	struct hyper_dmabuf_info_entry_imported *info_entry;
+	int bkt;
+	ssize_t count = 0;
+	size_t total = 0;
+
+	hash_for_each(hyper_dmabuf_hash_imported, bkt, info_entry, node) {
+		int id = info_entry->info->hyper_dmabuf_id;
+		int nents = info_entry->info->nents;
+		bool valid = info_entry->info->valid;
+		int num_importers = info_entry->info->num_importers;
+		total += nents;
+		count += scnprintf(buf + count, PAGE_SIZE - count, "id:%d, nents:%d, v:%c, numi:%d\n",
+				   id, nents, (valid ? 't' : 'f'), num_importers);
+	}
+	count += scnprintf(buf + count, PAGE_SIZE - count, "total nents: %lu\n",
+			   total);
+
+	return count;
+}
+
+static ssize_t hyper_dmabuf_exported_show(struct device *drv, struct device_attribute *attr, char *buf)
+{
+	struct hyper_dmabuf_info_entry_exported *info_entry;
+	int bkt;
+	ssize_t count = 0;
+	size_t total = 0;
+
+	hash_for_each(hyper_dmabuf_hash_exported, bkt, info_entry, node) {
+		int id = info_entry->info->hyper_dmabuf_id;
+		int nents = info_entry->info->nents;
+		bool valid = info_entry->info->valid;
+		int importer_exported = info_entry->info->importer_exported;
+		total += nents;
+		count += scnprintf(buf + count, PAGE_SIZE - count, "id:%d, nents:%d, v:%c, ie:%d\n",
+				   id, nents, (valid ? 't' : 'f'), importer_exported);
+	}
+	count += scnprintf(buf + count, PAGE_SIZE - count, "total nents: %lu\n",
+			   total);
+
+	return count;
+}
+
+static DEVICE_ATTR(imported, S_IRUSR, hyper_dmabuf_imported_show, NULL);
+static DEVICE_ATTR(exported, S_IRUSR, hyper_dmabuf_exported_show, NULL);
+
+int hyper_dmabuf_register_sysfs(struct device *dev)
+{
+	int err;
+
+	err = device_create_file(dev, &dev_attr_imported);
+	if (err < 0)
+		goto err1;
+	err = device_create_file(dev, &dev_attr_exported);
+	if (err < 0)
+		goto err2;
+
+	return 0;
+err2:
+	device_remove_file(dev, &dev_attr_imported);
+err1:
+	return -1;
+}
+
+int hyper_dmabuf_unregister_sysfs(struct device *dev)
+{
+	device_remove_file(dev, &dev_attr_imported);
+	device_remove_file(dev, &dev_attr_exported);
+	return 0;
+}
+#endif
+
 int hyper_dmabuf_table_init()
 {
 	hash_init(hyper_dmabuf_hash_imported);
diff --git a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.h b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.h
index f55d06e..a46f884 100644
--- a/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.h
+++ b/drivers/xen/hyper_dmabuf/hyper_dmabuf_list.h
@@ -37,4 +37,7 @@ int hyper_dmabuf_remove_exported(int id);
 
 int hyper_dmabuf_remove_imported(int id);
 
+int hyper_dmabuf_register_sysfs(struct device *dev);
+int hyper_dmabuf_unregister_sysfs(struct device *dev);
+
 #endif // __HYPER_DMABUF_LIST_H__
-- 
2.7.4