dma-buf: Delete the DMA-BUF attachment sysfs statistics

The DMA-BUF attachment statistics form a subset of the DMA-BUF
sysfs statistics that recently merged to the drm-misc tree. They are not
UABI yet since they have not merged to the upstream Linux kernel.

Since there has been a reported a performance regression due to the
overhead of sysfs directory creation/teardown during
dma_buf_attach()/dma_buf_detach(), this patch deletes the DMA-BUF
attachment statistics from sysfs.

Fixes: bdb8d06dfefd ("dmabuf: Add the capability to expose DMA-BUF stats in sysfs")
Signed-off-by: Hridya Valsaraju <hridya@google.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210713040742.2680135-1-hridya@google.com
Signed-off-by: Christian König <christian.koenig@amd.com>

1 files changed, 4 insertions, 136 deletions

diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
index a2638e84199c..053baadcada9 100644
--- a/drivers/dma-buf/dma-buf-sysfs-stats.c
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
@@ -40,14 +40,11 @@
  *
  * * ``/sys/kernel/dmabuf/buffers/<inode_number>/exporter_name``
  * * ``/sys/kernel/dmabuf/buffers/<inode_number>/size``
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/device``
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/map_counter``
  *
- * The information in the interface can also be used to derive per-exporter and
- * per-device usage statistics. The data from the interface can be gathered
- * on error conditions or other important events to provide a snapshot of
- * DMA-BUF usage. It can also be collected periodically by telemetry to monitor
- * various metrics.
+ * The information in the interface can also be used to derive per-exporter
+ * statistics. The data from the interface can be gathered on error conditions
+ * or other important events to provide a snapshot of DMA-BUF usage.
+ * It can also be collected periodically by telemetry to monitor various metrics.
  *
  * Detailed documentation about the interface is present in
  * Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers.
@@ -121,120 +118,6 @@ static struct kobj_type dma_buf_ktype = {
 	.default_groups = dma_buf_stats_default_groups,
 };
 
-#define to_dma_buf_attach_entry_from_kobj(x) container_of(x, struct dma_buf_attach_sysfs_entry, kobj)
-
-struct dma_buf_attach_stats_attribute {
-	struct attribute attr;
-	ssize_t (*show)(struct dma_buf_attach_sysfs_entry *sysfs_entry,
-			struct dma_buf_attach_stats_attribute *attr, char *buf);
-};
-#define to_dma_buf_attach_stats_attr(x) container_of(x, struct dma_buf_attach_stats_attribute, attr)
-
-static ssize_t dma_buf_attach_stats_attribute_show(struct kobject *kobj,
-						   struct attribute *attr,
-						   char *buf)
-{
-	struct dma_buf_attach_stats_attribute *attribute;
-	struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-	attribute = to_dma_buf_attach_stats_attr(attr);
-	sysfs_entry = to_dma_buf_attach_entry_from_kobj(kobj);
-
-	if (!attribute->show)
-		return -EIO;
-
-	return attribute->show(sysfs_entry, attribute, buf);
-}
-
-static const struct sysfs_ops dma_buf_attach_stats_sysfs_ops = {
-	.show = dma_buf_attach_stats_attribute_show,
-};
-
-static ssize_t map_counter_show(struct dma_buf_attach_sysfs_entry *sysfs_entry,
-				struct dma_buf_attach_stats_attribute *attr,
-				char *buf)
-{
-	return sysfs_emit(buf, "%u\n", sysfs_entry->map_counter);
-}
-
-static struct dma_buf_attach_stats_attribute map_counter_attribute =
-	__ATTR_RO(map_counter);
-
-static struct attribute *dma_buf_attach_stats_default_attrs[] = {
-	&map_counter_attribute.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(dma_buf_attach_stats_default);
-
-static void dma_buf_attach_sysfs_release(struct kobject *kobj)
-{
-	struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-	sysfs_entry = to_dma_buf_attach_entry_from_kobj(kobj);
-	kfree(sysfs_entry);
-}
-
-static struct kobj_type dma_buf_attach_ktype = {
-	.sysfs_ops = &dma_buf_attach_stats_sysfs_ops,
-	.release = dma_buf_attach_sysfs_release,
-	.default_groups = dma_buf_attach_stats_default_groups,
-};
-
-void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach)
-{
-	struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-	sysfs_entry = attach->sysfs_entry;
-	if (!sysfs_entry)
-		return;
-
-	sysfs_delete_link(&sysfs_entry->kobj, &attach->dev->kobj, "device");
-
-	kobject_del(&sysfs_entry->kobj);
-	kobject_put(&sysfs_entry->kobj);
-}
-
-int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
-			       unsigned int uid)
-{
-	struct dma_buf_attach_sysfs_entry *sysfs_entry;
-	int ret;
-	struct dma_buf *dmabuf;
-
-	if (!attach)
-		return -EINVAL;
-
-	dmabuf = attach->dmabuf;
-
-	sysfs_entry = kzalloc(sizeof(struct dma_buf_attach_sysfs_entry),
-			      GFP_KERNEL);
-	if (!sysfs_entry)
-		return -ENOMEM;
-
-	sysfs_entry->kobj.kset = dmabuf->sysfs_entry->attach_stats_kset;
-
-	attach->sysfs_entry = sysfs_entry;
-
-	ret = kobject_init_and_add(&sysfs_entry->kobj, &dma_buf_attach_ktype,
-				   NULL, "%u", uid);
-	if (ret)
-		goto kobj_err;
-
-	ret = sysfs_create_link(&sysfs_entry->kobj, &attach->dev->kobj,
-				"device");
-	if (ret)
-		goto link_err;
-
-	return 0;
-
-link_err:
-	kobject_del(&sysfs_entry->kobj);
-kobj_err:
-	kobject_put(&sysfs_entry->kobj);
-	attach->sysfs_entry = NULL;
-
-	return ret;
-}
 void dma_buf_stats_teardown(struct dma_buf *dmabuf)
 {
 	struct dma_buf_sysfs_entry *sysfs_entry;
@@ -243,7 +126,6 @@ void dma_buf_stats_teardown(struct dma_buf *dmabuf)
 	if (!sysfs_entry)
 		return;
 
-	kset_unregister(sysfs_entry->attach_stats_kset);
 	kobject_del(&sysfs_entry->kobj);
 	kobject_put(&sysfs_entry->kobj);
 }
@@ -290,7 +172,6 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
 {
 	struct dma_buf_sysfs_entry *sysfs_entry;
 	int ret;
-	struct kset *attach_stats_kset;
 
 	if (!dmabuf || !dmabuf->file)
 		return -EINVAL;
@@ -315,21 +196,8 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
 	if (ret)
 		goto err_sysfs_dmabuf;
 
-	/* create the directory for attachment stats */
-	attach_stats_kset = kset_create_and_add("attachments",
-						&dmabuf_sysfs_no_uevent_ops,
-						&sysfs_entry->kobj);
-	if (!attach_stats_kset) {
-		ret = -ENOMEM;
-		goto err_sysfs_attach;
-	}
-
-	sysfs_entry->attach_stats_kset = attach_stats_kset;
-
 	return 0;
 
-err_sysfs_attach:
-	kobject_del(&sysfs_entry->kobj);
 err_sysfs_dmabuf:
 	kobject_put(&sysfs_entry->kobj);
 	dmabuf->sysfs_entry = NULL;