+++ /dev/null
-// 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;
-}
projects / thirdparty / kernel / linux.git / commitdiff
