Overview
========
The patch adds DMA-BUF statistics to /sys/kernel/dmabuf/buffers. It
allows statistics to be enabled for each DMA-BUF in sysfs by enabling
the config CONFIG_DMABUF_SYSFS_STATS.
The following stats will be exposed by the interface:
/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 inode_number is unique for each DMA-BUF and was added earlier [1]
in order to allow userspace to track DMA-BUF usage across different
processes.
Use Cases
=========
The interface provides a way to gather DMA-BUF per-buffer statistics
from production devices. These statistics will be used to derive DMA-BUF
per-exporter stats and per-device usage stats for Android Bug reports.
The corresponding userspace changes can be found at [2].
Telemetry tools will also capture this information(along with other
memory metrics) periodically as well as on important events like a
foreground app kill (which might have been triggered by Low Memory
Killer). It will also contribute to provide a snapshot of the system
memory usage on other events such as OOM kills and Application Not
Responding events.
Background
==========
Currently, there are two existing interfaces that provide information
about DMA-BUFs.
1) /sys/kernel/debug/dma_buf/bufinfo
debugfs is however unsuitable to be mounted in production systems and
cannot be considered as an alternative to the sysfs interface being
proposed.
2) proc/<pid>/fdinfo/<fd>
The proc/<pid>/fdinfo/<fd> files expose information about DMA-BUF fds.
However, the existing procfs interfaces can only provide information
about the buffers for which processes hold fds or have the buffers
mmapped into their address space. Since the procfs interfaces alone
cannot provide a full picture of all DMA-BUFs in the system, there is
the need for an alternate interface to provide this information on
production systems.
The patch contains the following major improvements over v1:
1) Each attachment is represented by its own directory to allow creating
a symlink to the importing device and to also provide room for future
expansion.
2) The number of distinct mappings of each attachment is exposed in a
separate file.
3) The per-buffer statistics are now in /sys/kernel/dmabuf/buffers
inorder to make the interface expandable in future.
All of the improvements above are based on suggestions/feedback from
Daniel Vetter and Christian König.
A shell script that can be run on a classic Linux environment to read
out the DMA-BUF statistics can be found at [3](suggested by John
Stultz).
[1]: https://lore.kernel.org/patchwork/patch/1088791/
[2]: https://android-review.googlesource.com/q/topic:%22dmabuf-sysfs%22+(status:…
[3]: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo…
Reviewed-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Signed-off-by: Hridya Valsaraju <hridya(a)google.com>
Reported-by: kernel test robot <lkp(a)intel.com>
---
Hi Daniel,
I rewrote the commit message and added a new section to
Documentation/driver-api/dma-buf.rst as per your suggestions. Please
do take another look when you get a chance. Thanks again for the
guidance.
Regards,
Hridya
Change in v5:
-Added a section on DMA-BUF statistics to
Documentation/driver-api/dma-buf.rst. Organized the commit message to
clearly state the need for the new interface and provide the
background on why the existing means of DMA-BUF accounting will not
suffice. Based on feedback from Daniel Vetter.
Changes in v4:
-Suppress uevents from kset creation to avoid waking up uevent listeners
on DMA-BUF export/release.
Changes in v3:
-Fix a warning reported by the kernel test robot.
Changes in v2:
-Move statistics to /sys/kernel/dmabuf/buffers in oder to allow addition
of other DMA-BUF-related sysfs stats in future. Based on feedback from
Daniel Vetter.
-Each attachment has its own directory to represent attached devices as
symlinks and to introduce map_count as a separate file. Based on
feedback from Daniel Vetter and Christian König. Thank you both!
-Commit messages updated to point to userspace code in AOSP that will
read the DMA-BUF sysfs stats.
.../ABI/testing/sysfs-kernel-dmabuf-buffers | 52 +++
Documentation/driver-api/dma-buf.rst | 34 ++
drivers/dma-buf/Kconfig | 11 +
drivers/dma-buf/Makefile | 1 +
drivers/dma-buf/dma-buf-sysfs-stats.c | 300 ++++++++++++++++++
drivers/dma-buf/dma-buf-sysfs-stats.h | 62 ++++
drivers/dma-buf/dma-buf.c | 37 +++
include/linux/dma-buf.h | 20 ++
8 files changed, 517 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
create mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.c
create mode 100644 drivers/dma-buf/dma-buf-sysfs-stats.h
diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
new file mode 100644
index 000000000000..a243984ed420
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
@@ -0,0 +1,52 @@
+What: /sys/kernel/dmabuf/buffers
+Date: May 2021
+KernelVersion: v5.13
+Contact: Hridya Valsaraju <hridya(a)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(a)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(a)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(a)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(a)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(a)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(a)google.com>
+Description: This file is read-only and contains a map_counter indicating the
+ number of distinct device mappings of the attachment.
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
index 7f37ec30d9fd..4027762a824a 100644
--- a/Documentation/driver-api/dma-buf.rst
+++ b/Documentation/driver-api/dma-buf.rst
@@ -106,6 +106,40 @@ Implicit Fence Poll Support
.. kernel-doc:: drivers/dma-buf/dma-buf.c
:doc: implicit fence polling
+DMA-BUF statistics
+~~~~~~~~~~~~~~~~~~
+
+``/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``
+* ``/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.
+
+Detailed documentation about the interface is present in
+Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
+
Kernel Functions and Structures Reference
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig
index 4e16c71c24b7..9561e3d2d428 100644
--- a/drivers/dma-buf/Kconfig
+++ b/drivers/dma-buf/Kconfig
@@ -72,6 +72,17 @@ menuconfig DMABUF_HEAPS
allows userspace to allocate dma-bufs that can be shared
between drivers.
+menuconfig DMABUF_SYSFS_STATS
+ bool "DMA-BUF sysfs statistics"
+ select 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>.
+
source "drivers/dma-buf/heaps/Kconfig"
endmenu
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 995e05f609ff..40d81f23cacf 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -6,6 +6,7 @@ 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
new file mode 100644
index 000000000000..45717c8108c8
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
@@ -0,0 +1,300 @@
+// 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)
+
+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 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,
+};
+
+#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;
+
+ sysfs_entry = dmabuf->sysfs_entry;
+ if (!sysfs_entry)
+ return;
+
+ kset_unregister(sysfs_entry->attach_stats_kset);
+ kobject_del(&sysfs_entry->kobj);
+ kobject_put(&sysfs_entry->kobj);
+}
+
+
+/* Statistics files do not need to send uevents. */
+static int dmabuf_sysfs_uevent_filter(struct kset *kset, 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 dma_buf_sysfs_entry *sysfs_entry;
+ int ret;
+ struct kset *attach_stats_kset;
+
+ if (!dmabuf || !dmabuf->file)
+ return -EINVAL;
+
+ 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(dmabuf->file)->i_ino);
+ 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;
+ return ret;
+}
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
new file mode 100644
index 000000000000..5f4703249117
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
@@ -0,0 +1,62 @@
+/* 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);
+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)
+{
+ return 0;
+}
+
+static inline void dma_buf_uninit_sysfs_statistics(void) {}
+
+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
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index f264b70c383e..184dd7acb1ed 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -29,6 +29,8 @@
#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 *);
struct dma_buf_list {
@@ -79,6 +81,7 @@ static void dma_buf_release(struct dentry *dentry)
if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
dma_resv_fini(dmabuf->resv);
+ dma_buf_stats_teardown(dmabuf);
module_put(dmabuf->owner);
kfree(dmabuf->name);
kfree(dmabuf);
@@ -580,6 +583,10 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
file->f_mode |= FMODE_LSEEK;
dmabuf->file = file;
+ ret = dma_buf_stats_setup(dmabuf);
+ if (ret)
+ goto err_sysfs;
+
mutex_init(&dmabuf->lock);
INIT_LIST_HEAD(&dmabuf->attachments);
@@ -589,6 +596,14 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
return dmabuf;
+err_sysfs:
+ /*
+ * Set file->f_path.dentry->d_fsdata to NULL so that when
+ * dma_buf_release() gets invoked by dentry_ops, it exits
+ * early before calling the release() dma_buf op.
+ */
+ file->f_path.dentry->d_fsdata = NULL;
+ fput(file);
err_dmabuf:
kfree(dmabuf);
err_module:
@@ -723,6 +738,7 @@ 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);
@@ -748,8 +764,13 @@ 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.
@@ -776,6 +797,7 @@ 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;
@@ -792,6 +814,7 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
if (dma_buf_is_dynamic(attach->dmabuf))
dma_resv_unlock(attach->dmabuf->resv);
+err_sysfs:
dma_buf_detach(dmabuf, attach);
return ERR_PTR(ret);
}
@@ -841,6 +864,7 @@ 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)) {
dma_buf_unpin(attach);
@@ -854,6 +878,7 @@ 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);
@@ -993,6 +1018,9 @@ 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);
@@ -1030,6 +1058,8 @@ 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);
@@ -1480,6 +1510,12 @@ 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);
@@ -1495,5 +1531,6 @@ 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);
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index efdc56b9d95f..342585bd6dff 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -295,6 +295,9 @@ struct dma_buf_ops {
* @poll: for userspace poll support
* @cb_excl: for userspace poll support
* @cb_shared: for userspace poll support
+ * @sysfs_entry: for exposing information about this buffer in sysfs.
+ * The attachment_uid member of @sysfs_entry is protected by dma_resv lock
+ * and is incremented on each attach.
*
* This represents a shared buffer, created by calling dma_buf_export(). The
* userspace representation is a normal file descriptor, which can be created by
@@ -330,6 +333,15 @@ struct dma_buf {
__poll_t active;
} cb_excl, cb_shared;
+#ifdef CONFIG_DMABUF_SYSFS_STATS
+ /* for sysfs stats */
+ struct dma_buf_sysfs_entry {
+ struct kobject kobj;
+ struct dma_buf *dmabuf;
+ unsigned int attachment_uid;
+ struct kset *attach_stats_kset;
+ } *sysfs_entry;
+#endif
};
/**
@@ -379,6 +391,7 @@ 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
@@ -399,6 +412,13 @@ 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
};
/**
--
2.32.0.rc0.204.g9fa02ecfa5-goog
tldr; DMA buffers aren't normal memory, expecting that you can use
them like that (like calling get_user_pages works, or that they're
accounting like any other normal memory) cannot be guaranteed.
Since some userspace only runs on integrated devices, where all
buffers are actually all resident system memory, there's a huge
temptation to assume that a struct page is always present and useable
like for any more pagecache backed mmap. This has the potential to
result in a uapi nightmare.
To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which
blocks get_user_pages and all the other struct page based
infrastructure for everyone. In spirit this is the uapi counterpart to
the kernel-internal CONFIG_DMABUF_DEBUG.
Motivated by a recent patch which wanted to swich the system dma-buf
heap to vm_insert_page instead of vm_insert_pfn.
v2:
Jason brought up that we also want to guarantee that all ptes have the
pte_special flag set, to catch fast get_user_pages (on architectures
that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would
still allow vm_insert_page, but limiting to VM_PFNMAP will catch that.
>From auditing the various functions to insert pfn pte entires
(vm_insert_pfn_prot, remap_pfn_range and all it's callers like
dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so
this should be the correct flag to check for.
References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-Wb…
Acked-by: Christian König <christian.koenig(a)amd.com>
Cc: Jason Gunthorpe <jgg(a)ziepe.ca>
Cc: Suren Baghdasaryan <surenb(a)google.com>
Cc: Matthew Wilcox <willy(a)infradead.org>
Cc: John Stultz <john.stultz(a)linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: "Christian König" <christian.koenig(a)amd.com>
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
--
Resending this so I can test the next two patches for vgem/shmem in
intel-gfx-ci. Last round failed somehow, but I can't repro that at all
locally here.
No immediate plans to merge this patch here since ttm isn't addressed
yet (and there we have the hugepte issue, for which I don't think we
have a clear consensus yet).
-Daniel
---
drivers/dma-buf/dma-buf.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index eadd1eaa2fb5..dda583fb1f03 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -127,6 +127,7 @@ static struct file_system_type dma_buf_fs_type = {
static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
{
struct dma_buf *dmabuf;
+ int ret;
if (!is_dma_buf_file(file))
return -EINVAL;
@@ -142,7 +143,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
dmabuf->size >> PAGE_SHIFT)
return -EINVAL;
- return dmabuf->ops->mmap(dmabuf, vma);
+ ret = dmabuf->ops->mmap(dmabuf, vma);
+
+ WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+ return ret;
}
static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
@@ -1244,6 +1249,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
unsigned long pgoff)
{
+ int ret;
+
if (WARN_ON(!dmabuf || !vma))
return -EINVAL;
@@ -1264,7 +1271,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
vma_set_file(vma, dmabuf->file);
vma->vm_pgoff = pgoff;
- return dmabuf->ops->mmap(dmabuf, vma);
+ ret = dmabuf->ops->mmap(dmabuf, vma);
+
+ WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+ return ret;
}
EXPORT_SYMBOL_GPL(dma_buf_mmap);
--
2.31.0
Fixes the following W=1 kernel build warning(s):
drivers/gpu/drm/vgem/vgem_drv.c:47: warning: expecting prototype for This is vgem, a (non-hardware(). Prototype was for DRIVER_NAME() instead
Cc: David Airlie <airlied(a)linux.ie>
Cc: Daniel Vetter <daniel(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: "Christian König" <christian.koenig(a)amd.com>
Cc: Adam Jackson <ajax(a)redhat.com>
Cc: Ben Widawsky <ben(a)bwidawsk.net>
Cc: dri-devel(a)lists.freedesktop.org
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
Signed-off-by: Lee Jones <lee.jones(a)linaro.org>
---
drivers/gpu/drm/vgem/vgem_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index a0e75f1d5d016..bf38a7e319d14 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -25,7 +25,7 @@
* Ben Widawsky <ben(a)bwidawsk.net>
*/
-/**
+/*
* This is vgem, a (non-hardware-backed) GEM service. This is used by Mesa's
* software renderer and the X server for efficient buffer sharing.
*/
--
2.31.1
Fixes the following W=1 kernel build warning(s):
drivers/gpu/drm/msm/msm_gem.c:364: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
drivers/gpu/drm/msm/msm_gem.c:763: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
Cc: Rob Clark <robdclark(a)gmail.com>
Cc: Sean Paul <sean(a)poorly.run>
Cc: David Airlie <airlied(a)linux.ie>
Cc: Daniel Vetter <daniel(a)ffwll.ch>
Cc: Sumit Semwal <sumit.semwal(a)linaro.org>
Cc: "Christian König" <christian.koenig(a)amd.com>
Cc: linux-arm-msm(a)vger.kernel.org
Cc: dri-devel(a)lists.freedesktop.org
Cc: freedreno(a)lists.freedesktop.org
Cc: linux-media(a)vger.kernel.org
Cc: linaro-mm-sig(a)lists.linaro.org
Signed-off-by: Lee Jones <lee.jones(a)linaro.org>
---
drivers/gpu/drm/msm/msm_gem.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 56df86e5f7400..15434deb19334 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -372,7 +372,7 @@ static void del_vma(struct msm_gem_vma *vma)
kfree(vma);
}
-/**
+/*
* If close is true, this also closes the VMA (releasing the allocated
* iova range) in addition to removing the iommu mapping. In the eviction
* case (!close), we keep the iova allocated, but only remove the iommu
@@ -773,7 +773,7 @@ void msm_gem_purge(struct drm_gem_object *obj)
0, (loff_t)-1);
}
-/**
+/*
* Unpin the backing pages and make them available to be swapped out.
*/
void msm_gem_evict(struct drm_gem_object *obj)
--
2.31.1
In the function amdgpu_uvd_cs_msg(), every branch in the switch
statement will have a return, so the code below the switch statement
will not be executed.
Eliminate the follow smatch warning:
drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c:845 amdgpu_uvd_cs_msg() warn:
ignoring unreachable code.
Reported-by: Abaci Robot <abaci(a)linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong(a)linux.alibaba.com>
---
Changes in v2:
-For the follow advice: https://lore.kernel.org/patchwork/patch/1435968/
drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
index c6dbc08..35f6874 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c
@@ -829,9 +829,8 @@ static int amdgpu_uvd_cs_msg(struct amdgpu_uvd_cs_ctx *ctx,
default:
DRM_ERROR("Illegal UVD message type (%d)!\n", msg_type);
- return -EINVAL;
}
- BUG();
+
return -EINVAL;
}
--
1.8.3.1
Hi Patrice, Pierre-Yves, Alain
On Tue, Jun 1, 2021 at 7:43 PM Patrice CHOTARD
<patrice.chotard(a)foss.st.com> wrote:
>
> Hi Dillon
>
> On 5/14/21 1:02 PM, dillon.minfei(a)gmail.com wrote:
> > From: Dillon Min <dillon.minfei(a)gmail.com>
> >
> > As stm32f429's internal flash is 2Mbytes and compiled kernel
> > image bigger than 2Mbytes, so we have to load kernel image
> > to sdram on stm32f429-disco board which has 8Mbytes sdram space.
> >
> > based on above context, as you knows kernel running on external
> > sdram is more slower than internal flash. besides, we need read 4
> > bytes to get touch screen xyz(x, y, pressure) coordinate data in
> > stmpe811 interrupt.
> >
> > so, in stm32f4_i2c_handle_rx_done, as i2c read slower than running
> > in xip mode, have to adjust 'STOP/START bit set position' from last
> > two bytes to last one bytes. else, will get i2c timeout in reading
> > touch screen coordinate.
> >
> > to not bring in side effect, introduce IIC_LAST_BYTE_POS to support xip
> > kernel or zImage.
> >
> > Fixes: 62817fc8d282 ("i2c: stm32f4: add driver")
> > Link: https://lore.kernel.org/lkml/1591709203-12106-5-git-send-email-dillon.minfe…
> > Signed-off-by: Dillon Min <dillon.minfei(a)gmail.com>
> > ---
> > drivers/i2c/busses/i2c-stm32f4.c | 12 +++++++++---
> > 1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-stm32f4.c b/drivers/i2c/busses/i2c-stm32f4.c
> > index 4933fc8ce3fd..2e41231b9037 100644
> > --- a/drivers/i2c/busses/i2c-stm32f4.c
> > +++ b/drivers/i2c/busses/i2c-stm32f4.c
> > @@ -93,6 +93,12 @@
> > #define STM32F4_I2C_MAX_FREQ 46U
> > #define HZ_TO_MHZ 1000000
> >
> > +#if !defined(CONFIG_MMU) && !defined(CONFIG_XIP_KERNEL)
> > +#define IIC_LAST_BYTE_POS 1
> > +#else
> > +#define IIC_LAST_BYTE_POS 2
> > +#endif
> > +
> > /**
> > * struct stm32f4_i2c_msg - client specific data
> > * @addr: 8-bit slave addr, including r/w bit
> > @@ -439,7 +445,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> > int i;
> >
> > switch (msg->count) {
> > - case 2:
> > + case IIC_LAST_BYTE_POS:
> > /*
> > * In order to correctly send the Stop or Repeated Start
> > * condition on the I2C bus, the STOP/START bit has to be set
> > @@ -454,7 +460,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> > else
> > stm32f4_i2c_set_bits(reg, STM32F4_I2C_CR1_START);
> >
> > - for (i = 2; i > 0; i--)
> > + for (i = IIC_LAST_BYTE_POS; i > 0; i--)
> > stm32f4_i2c_read_msg(i2c_dev);
> >
> > reg = i2c_dev->base + STM32F4_I2C_CR2;
> > @@ -463,7 +469,7 @@ static void stm32f4_i2c_handle_rx_done(struct stm32f4_i2c_dev *i2c_dev)
> >
> > complete(&i2c_dev->complete);
> > break;
> > - case 3:
> > + case (IIC_LAST_BYTE_POS+1):
> > /*
> > * In order to correctly generate the NACK pulse after the last
> > * received data byte, we have to enable NACK before reading N-2
> >
>
> I tested this patch on STM32F429-Disco, it fixes the issue described by Dillon.
> But i think it's not a good idea to make usage of #if !defined(CONFIG_MMU) && !defined(CONFIG_XIP_KERNEL)
> inside the driver code.
Hi Patrice,
Thanks for your time.
How about introducing a dts node for this purpose.
like
stm32-i2c,last-byte-pos = <1>;
or
stm32-i2c,last-byte-pos = <2>;
if not set, the default value is 2
Best Regards
Dillon
>
> Pierre-Yves, Alain, as i am not I2C expert, can you have a look at this patch and propose another solution
> to fix the original issue described by Dillon ?
>
> Thanks
> Patrice