[RFC,4/4] RFC: dma-buf: Remove DMA-BUF statistics

diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
deleted file mode 100644
index 5d3bc997dc64..000000000000
--- a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
+++ /dev/null
@@ -1,24 +0,0 @@ 
-What:		/sys/kernel/dmabuf/buffers
-Date:		May 2021
-KernelVersion:	v5.13
-Contact:	Hridya Valsaraju <hridya@google.com>
-Description:	The /sys/kernel/dmabuf/buffers directory contains a
-		snapshot of the internal state of every DMA-BUF.
-		/sys/kernel/dmabuf/buffers/<inode_number> will contain the
-		statistics for the DMA-BUF with the unique inode number
-		<inode_number>
-Users:		kernel memory tuning/debugging tools
-
-What:		/sys/kernel/dmabuf/buffers/<inode_number>/exporter_name
-Date:		May 2021
-KernelVersion:	v5.13
-Contact:	Hridya Valsaraju <hridya@google.com>
-Description:	This file is read-only and contains the name of the exporter of
-		the DMA-BUF.
-
-What:		/sys/kernel/dmabuf/buffers/<inode_number>/size
-Date:		May 2021
-KernelVersion:	v5.13
-Contact:	Hridya Valsaraju <hridya@google.com>
-Description:	This file is read-only and specifies the size of the DMA-BUF in
-		bytes.
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index 29abf1eebf9f..2f36c21d9948 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -125,11 +125,6 @@  Implicit Fence Poll Support
 .. kernel-doc:: drivers/dma-buf/dma-buf.c
    :doc: implicit fence polling
 
-DMA-BUF statistics
-~~~~~~~~~~~~~~~~~~
-.. kernel-doc:: drivers/dma-buf/dma-buf-sysfs-stats.c
-   :doc: overview
-
 DMA Buffer ioctls
 ~~~~~~~~~~~~~~~~~
 
diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
index fee04fdb0822..03e38c0d1fff 100644
--- a/drivers/dma-buf/Kconfig
+++ b/drivers/dma-buf/Kconfig
@@ -76,21 +76,6 @@  menuconfig DMABUF_HEAPS
 	  allows userspace to allocate dma-bufs that can be shared
 	  between drivers.
 
-menuconfig DMABUF_SYSFS_STATS
-	bool "DMA-BUF sysfs statistics (DEPRECATED)"
-	depends on DMA_SHARED_BUFFER
-	help
-	   Choose this option to enable DMA-BUF sysfs statistics
-	   in location /sys/kernel/dmabuf/buffers.
-
-	   /sys/kernel/dmabuf/buffers/<inode_number> will contain
-	   statistics for the DMA-BUF with the unique inode number
-	   <inode_number>.
-
-	   This option is deprecated and should sooner or later be removed.
-	   Android is the only user of this and it turned out that this resulted
-	   in quite some performance problems.
-
 source "drivers/dma-buf/heaps/Kconfig"
 
 endmenu
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 70ec901edf2c..8ab2bfecb1c9 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -6,7 +6,6 @@  obj-$(CONFIG_DMABUF_HEAPS)	+= heaps/
 obj-$(CONFIG_SYNC_FILE)		+= sync_file.o
 obj-$(CONFIG_SW_SYNC)		+= sw_sync.o sync_debug.o
 obj-$(CONFIG_UDMABUF)		+= udmabuf.o
-obj-$(CONFIG_DMABUF_SYSFS_STATS) += dma-buf-sysfs-stats.o
 
 dmabuf_selftests-y := \
 	selftest.o \
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
deleted file mode 100644
index b5b62e40ccc1..000000000000
--- a/drivers/dma-buf/dma-buf-sysfs-stats.c
+++ /dev/null
@@ -1,202 +0,0 @@ 
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * DMA-BUF sysfs statistics.
- *
- * Copyright (C) 2021 Google LLC.
- */
-
-#include <linux/dma-buf.h>
-#include <linux/dma-resv.h>
-#include <linux/kobject.h>
-#include <linux/printk.h>
-#include <linux/slab.h>
-#include <linux/sysfs.h>
-
-#include "dma-buf-sysfs-stats.h"
-
-#define to_dma_buf_entry_from_kobj(x) container_of(x, struct dma_buf_sysfs_entry, kobj)
-
-/**
- * DOC: overview
- *
- * ``/sys/kernel/debug/dma_buf/bufinfo`` provides an overview of every DMA-BUF
- * in the system. However, since debugfs is not safe to be mounted in
- * production, procfs and sysfs can be used to gather DMA-BUF statistics on
- * production systems.
- *
- * The ``/proc/<pid>/fdinfo/<fd>`` files in procfs can be used to gather
- * information about DMA-BUF fds. Detailed documentation about the interface
- * is present in Documentation/filesystems/proc.rst.
- *
- * Unfortunately, the existing procfs interfaces can only provide information
- * about the DMA-BUFs for which processes hold fds or have the buffers mmapped
- * into their address space. This necessitated the creation of the DMA-BUF sysfs
- * statistics interface to provide per-buffer information on production systems.
- *
- * The interface at ``/sys/kernel/dmabuf/buffers`` exposes information about
- * every DMA-BUF when ``CONFIG_DMABUF_SYSFS_STATS`` is enabled.
- *
- * The following stats are exposed by the interface:
- *
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/exporter_name``
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/size``
- *
- * 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.
- */
-
-struct dma_buf_stats_attribute {
-	struct attribute attr;
-	ssize_t (*show)(struct dma_buf *dmabuf,
-			struct dma_buf_stats_attribute *attr, char *buf);
-};
-#define to_dma_buf_stats_attr(x) container_of(x, struct dma_buf_stats_attribute, attr)
-
-static ssize_t dma_buf_stats_attribute_show(struct kobject *kobj,
-					    struct attribute *attr,
-					    char *buf)
-{
-	struct dma_buf_stats_attribute *attribute;
-	struct dma_buf_sysfs_entry *sysfs_entry;
-	struct dma_buf *dmabuf;
-
-	attribute = to_dma_buf_stats_attr(attr);
-	sysfs_entry = to_dma_buf_entry_from_kobj(kobj);
-	dmabuf = sysfs_entry->dmabuf;
-
-	if (!dmabuf || !attribute->show)
-		return -EIO;
-
-	return attribute->show(dmabuf, attribute, buf);
-}
-
-static const struct sysfs_ops dma_buf_stats_sysfs_ops = {
-	.show = dma_buf_stats_attribute_show,
-};
-
-static ssize_t exporter_name_show(struct dma_buf *dmabuf,
-				  struct dma_buf_stats_attribute *attr,
-				  char *buf)
-{
-	return sysfs_emit(buf, "%s\n", dmabuf->exp_name);
-}
-
-static ssize_t size_show(struct dma_buf *dmabuf,
-			 struct dma_buf_stats_attribute *attr,
-			 char *buf)
-{
-	return sysfs_emit(buf, "%zu\n", dmabuf->size);
-}
-
-static struct dma_buf_stats_attribute exporter_name_attribute =
-	__ATTR_RO(exporter_name);
-static struct dma_buf_stats_attribute size_attribute = __ATTR_RO(size);
-
-static struct attribute *dma_buf_stats_default_attrs[] = {
-	&exporter_name_attribute.attr,
-	&size_attribute.attr,
-	NULL,
-};
-ATTRIBUTE_GROUPS(dma_buf_stats_default);
-
-static void dma_buf_sysfs_release(struct kobject *kobj)
-{
-	struct dma_buf_sysfs_entry *sysfs_entry;
-
-	sysfs_entry = to_dma_buf_entry_from_kobj(kobj);
-	kfree(sysfs_entry);
-}
-
-static const struct kobj_type dma_buf_ktype = {
-	.sysfs_ops = &dma_buf_stats_sysfs_ops,
-	.release = dma_buf_sysfs_release,
-	.default_groups = dma_buf_stats_default_groups,
-};
-
-void dma_buf_stats_teardown(struct dma_buf *dmabuf)
-{
-	struct dma_buf_sysfs_entry *sysfs_entry;
-
-	sysfs_entry = dmabuf->sysfs_entry;
-	if (!sysfs_entry)
-		return;
-
-	kobject_del(&sysfs_entry->kobj);
-	kobject_put(&sysfs_entry->kobj);
-}
-
-
-/* Statistics files do not need to send uevents. */
-static int dmabuf_sysfs_uevent_filter(const struct kobject *kobj)
-{
-	return 0;
-}
-
-static const struct kset_uevent_ops dmabuf_sysfs_no_uevent_ops = {
-	.filter = dmabuf_sysfs_uevent_filter,
-};
-
-static struct kset *dma_buf_stats_kset;
-static struct kset *dma_buf_per_buffer_stats_kset;
-int dma_buf_init_sysfs_statistics(void)
-{
-	dma_buf_stats_kset = kset_create_and_add("dmabuf",
-						 &dmabuf_sysfs_no_uevent_ops,
-						 kernel_kobj);
-	if (!dma_buf_stats_kset)
-		return -ENOMEM;
-
-	dma_buf_per_buffer_stats_kset = kset_create_and_add("buffers",
-							    &dmabuf_sysfs_no_uevent_ops,
-							    &dma_buf_stats_kset->kobj);
-	if (!dma_buf_per_buffer_stats_kset) {
-		kset_unregister(dma_buf_stats_kset);
-		return -ENOMEM;
-	}
-
-	return 0;
-}
-
-void dma_buf_uninit_sysfs_statistics(void)
-{
-	kset_unregister(dma_buf_per_buffer_stats_kset);
-	kset_unregister(dma_buf_stats_kset);
-}
-
-int dma_buf_stats_setup(struct dma_buf *dmabuf, struct file *file)
-{
-	struct dma_buf_sysfs_entry *sysfs_entry;
-	int ret;
-
-	if (!dmabuf->exp_name) {
-		pr_err("exporter name must not be empty if stats needed\n");
-		return -EINVAL;
-	}
-
-	sysfs_entry = kzalloc(sizeof(struct dma_buf_sysfs_entry), GFP_KERNEL);
-	if (!sysfs_entry)
-		return -ENOMEM;
-
-	sysfs_entry->kobj.kset = dma_buf_per_buffer_stats_kset;
-	sysfs_entry->dmabuf = dmabuf;
-
-	dmabuf->sysfs_entry = sysfs_entry;
-
-	/* create the directory for buffer stats */
-	ret = kobject_init_and_add(&sysfs_entry->kobj, &dma_buf_ktype, NULL,
-				   "%lu", file_inode(file)->i_ino);
-	if (ret)
-		goto err_sysfs_dmabuf;
-
-	return 0;
-
-err_sysfs_dmabuf:
-	kobject_put(&sysfs_entry->kobj);
-	dmabuf->sysfs_entry = NULL;
-	return ret;
-}
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
deleted file mode 100644
index 7a8a995b75ba..000000000000
--- a/drivers/dma-buf/dma-buf-sysfs-stats.h
+++ /dev/null
@@ -1,35 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * DMA-BUF sysfs statistics.
- *
- * Copyright (C) 2021 Google LLC.
- */
-
-#ifndef _DMA_BUF_SYSFS_STATS_H
-#define _DMA_BUF_SYSFS_STATS_H
-
-#ifdef CONFIG_DMABUF_SYSFS_STATS
-
-int dma_buf_init_sysfs_statistics(void);
-void dma_buf_uninit_sysfs_statistics(void);
-
-int dma_buf_stats_setup(struct dma_buf *dmabuf, struct file *file);
-
-void dma_buf_stats_teardown(struct dma_buf *dmabuf);
-#else
-
-static inline int dma_buf_init_sysfs_statistics(void)
-{
-	return 0;
-}
-
-static inline void dma_buf_uninit_sysfs_statistics(void) {}
-
-static inline int dma_buf_stats_setup(struct dma_buf *dmabuf, struct file *file)
-{
-	return 0;
-}
-
-static inline void dma_buf_stats_teardown(struct dma_buf *dmabuf) {}
-#endif
-#endif // _DMA_BUF_SYSFS_STATS_H
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index affb47eb8629..c51967c6cf85 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -31,8 +31,6 @@ 
 #include <uapi/linux/dma-buf.h>
 #include <uapi/linux/magic.h>
 
-#include "dma-buf-sysfs-stats.h"
-
 static inline int is_dma_buf_file(struct file *);
 
 #if IS_ENABLED(CONFIG_DEBUG_FS)
@@ -98,7 +96,6 @@  static void dma_buf_release(struct dentry *dentry)
 	 */
 	BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
 
-	dma_buf_stats_teardown(dmabuf);
 	dmabuf->ops->release(dmabuf);
 
 	if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
@@ -681,10 +678,6 @@  struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 		dmabuf->resv = resv;
 	}
 
-	ret = dma_buf_stats_setup(dmabuf, file);
-	if (ret)
-		goto err_dmabuf;
-
 	file->private_data = dmabuf;
 	file->f_path.dentry->d_fsdata = dmabuf;
 	dmabuf->file = file;
@@ -693,10 +686,6 @@  struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 
 	return dmabuf;
 
-err_dmabuf:
-	if (!resv)
-		dma_resv_fini(dmabuf->resv);
-	kfree(dmabuf);
 err_file:
 	fput(file);
 err_module:
@@ -1727,12 +1716,6 @@  static inline void dma_buf_uninit_debugfs(void)
 
 static int __init dma_buf_init(void)
 {
-	int ret;
-
-	ret = dma_buf_init_sysfs_statistics();
-	if (ret)
-		return ret;
-
 	dma_buf_mnt = kern_mount(&dma_buf_fs_type);
 	if (IS_ERR(dma_buf_mnt))
 		return PTR_ERR(dma_buf_mnt);
@@ -1746,6 +1729,5 @@  static void __exit dma_buf_deinit(void)
 {
 	dma_buf_uninit_debugfs();
 	kern_unmount(dma_buf_mnt);
-	dma_buf_uninit_sysfs_statistics();
 }
 __exitcall(dma_buf_deinit);