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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: bdb8d06dfe ("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>
This commit is contained in:
Hridya Valsaraju 2021-07-12 21:07:38 -07:00 committed by Christian König
parent 613ba71619
commit c715def515
5 changed files with 4 additions and 224 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
View File

@ -22,31 +22,3 @@ 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.
What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments
Date: May 2021
KernelVersion: v5.13
Contact: Hridya Valsaraju <hridya@google.com>
Description: This directory will contain subdirectories representing every
attachment of the DMA-BUF.
What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>
Date: May 2021
KernelVersion: v5.13
Contact: Hridya Valsaraju <hridya@google.com>
Description: This directory will contain information on the attached device
and the number of current distinct device mappings.
What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/device
Date: May 2021
KernelVersion: v5.13
Contact: Hridya Valsaraju <hridya@google.com>
Description: This file is read-only and is a symlink to the attached device's
sysfs entry.
What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/map_counter
Date: May 2021
KernelVersion: v5.13
Contact: Hridya Valsaraju <hridya@google.com>
Description: This file is read-only and contains a map_counter indicating the
number of distinct device mappings of the attachment.

140
drivers/dma-buf/dma-buf-sysfs-stats.c
View File

@ -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;

27
drivers/dma-buf/dma-buf-sysfs-stats.h
View File

@ -14,23 +14,8 @@ int dma_buf_init_sysfs_statistics(void);
void dma_buf_uninit_sysfs_statistics(void);
int dma_buf_stats_setup(struct dma_buf *dmabuf);
int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
unsigned int uid);
static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
int delta)
{
struct dma_buf_attach_sysfs_entry *entry = attach->sysfs_entry;
entry->map_counter += delta;
}
void dma_buf_stats_teardown(struct dma_buf *dmabuf);
void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach);
static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
{
struct dma_buf_sysfs_entry *entry = dmabuf->sysfs_entry;
return entry->attachment_uid++;
}
#else
static inline int dma_buf_init_sysfs_statistics(void)
@ -44,19 +29,7 @@ static inline int dma_buf_stats_setup(struct dma_buf *dmabuf)
{
return 0;
}
static inline int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
unsigned int uid)
{
return 0;
}
static inline void dma_buf_stats_teardown(struct dma_buf *dmabuf) {}
static inline void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach) {}
static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
int delta) {}
static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
{
return 0;
}
#endif
#endif // _DMA_BUF_SYSFS_STATS_H

16
drivers/dma-buf/dma-buf.c
View File

@ -738,7 +738,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
{
struct dma_buf_attachment *attach;
int ret;
unsigned int attach_uid;
if (WARN_ON(!dmabuf || !dev))
return ERR_PTR(-EINVAL);
@ -764,13 +763,8 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
}
dma_resv_lock(dmabuf->resv, NULL);
list_add(&attach->node, &dmabuf->attachments);
attach_uid = dma_buf_update_attach_uid(dmabuf);
dma_resv_unlock(dmabuf->resv);
ret = dma_buf_attach_stats_setup(attach, attach_uid);
if (ret)
goto err_sysfs;
/* When either the importer or the exporter can't handle dynamic
* mappings we cache the mapping here to avoid issues with the
* reservation object lock.
@ -797,7 +791,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
dma_resv_unlock(attach->dmabuf->resv);
attach->sgt = sgt;
attach->dir = DMA_BIDIRECTIONAL;
dma_buf_update_attachment_map_count(attach, 1 /* delta */);
}
return attach;
@ -814,7 +807,6 @@ err_unlock:
if (dma_buf_is_dynamic(attach->dmabuf))
dma_resv_unlock(attach->dmabuf->resv);
err_sysfs:
dma_buf_detach(dmabuf, attach);
return ERR_PTR(ret);
}
@ -864,7 +856,6 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
dma_resv_lock(attach->dmabuf->resv, NULL);
__unmap_dma_buf(attach, attach->sgt, attach->dir);
dma_buf_update_attachment_map_count(attach, -1 /* delta */);
if (dma_buf_is_dynamic(attach->dmabuf)) {
dmabuf->ops->unpin(attach);
@ -878,7 +869,6 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
if (dmabuf->ops->detach)
dmabuf->ops->detach(dmabuf, attach);
dma_buf_attach_stats_teardown(attach);
kfree(attach);
}
EXPORT_SYMBOL_GPL(dma_buf_detach);
@ -1020,10 +1010,6 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
}
}
#endif /* CONFIG_DMA_API_DEBUG */
if (!IS_ERR(sg_table))
dma_buf_update_attachment_map_count(attach, 1 /* delta */);
return sg_table;
}
EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
@ -1061,8 +1047,6 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
if (dma_buf_is_dynamic(attach->dmabuf) &&
!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
dma_buf_unpin(attach);
dma_buf_update_attachment_map_count(attach, -1 /* delta */);
}
EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);

17
include/linux/dma-buf.h
View File

@ -444,15 +444,6 @@ struct dma_buf {
struct dma_buf_sysfs_entry {
struct kobject kobj;
struct dma_buf *dmabuf;
/**
* @sysfs_entry.attachment_uid:
*
* This is protected by the dma_resv_lock() on @resv and is
* incremented on each attach.
*/
unsigned int attachment_uid;
struct kset *attach_stats_kset;
} *sysfs_entry;
#endif
};
@ -504,7 +495,6 @@ struct dma_buf_attach_ops {
* @importer_ops: importer operations for this attachment, if provided
* dma_buf_map/unmap_attachment() must be called with the dma_resv lock held.
* @importer_priv: importer specific attachment data.
* @sysfs_entry: For exposing information about this attachment in sysfs.
*
* This structure holds the attachment information between the dma_buf buffer
* and its user device(s). The list contains one attachment struct per device
@ -525,13 +515,6 @@ struct dma_buf_attachment {
const struct dma_buf_attach_ops *importer_ops;
void *importer_priv;
void *priv;
#ifdef CONFIG_DMABUF_SYSFS_STATS
/* for sysfs stats */
struct dma_buf_attach_sysfs_entry {
struct kobject kobj;
unsigned int map_counter;
} *sysfs_entry;
#endif
};
/**