On Thu, Jun 03, 2021 at 02:47:51PM -0700, Hridya Valsaraju wrote: > 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:open%20OR%20status:merged) > [3]: https://android-review.googlesource.com/c/platform/system/memory/libmeminfo/+/1549734 > > Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Hridya Valsaraju <hridya@xxxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > --- > > Hello Daniel, > > I have added the documentation as a DOC: overview section in the > dma-buf-sysfs-stats.c file as per your suggestion. Please do take a look > when you get a chance. Thanks in advance! > > Regards, > Hridya > > Change in v6: > -Moved documentation content from Documentation/driver-api/dma-buf.rst > to drivers/dma-buf/dma-buf-sysfs-stats.c as a DOC section and linked to > it from Documentation/driver-api/dma-buf.rst. Based on feedback from > Daniel Vetter. > > 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. Pushed to drm-misc-next, thanks for your work. I think the timing just conspired that this might miss the next merge window though :-/ -Daniel > > .../ABI/testing/sysfs-kernel-dmabuf-buffers | 52 +++ > Documentation/driver-api/dma-buf.rst | 5 + > drivers/dma-buf/Kconfig | 11 + > drivers/dma-buf/Makefile | 1 + > drivers/dma-buf/dma-buf-sysfs-stats.c | 337 ++++++++++++++++++ > 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, 525 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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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@xxxxxxxxxx> > +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..d47a429dc549 100644 > --- a/Documentation/driver-api/dma-buf.rst > +++ b/Documentation/driver-api/dma-buf.rst > @@ -106,6 +106,11 @@ 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 > + > 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..a2638e84199c > --- /dev/null > +++ b/drivers/dma-buf/dma-buf-sysfs-stats.c > @@ -0,0 +1,337 @@ > +// 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`` > + * * ``/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. > + */ > + > +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.rc1.229.g3e70b5a671-goog > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
