1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
// 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/dma-buf/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;
}
|
