On Wed, Jan 20, 2021 at 4:22 AM Christian König <ckoenig.leichtzumerken@xxxxxxxxx> wrote: > > Am 19.01.21 um 23:57 schrieb Hridya Valsaraju: > > This patch 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. > > > > Currently, this information is exposed in > > /sys/kernel/debug/dma_buf/bufinfo. > > However, since debugfs is considered unsafe to be mounted in production, > > it is being duplicated in sysfs. > > > > This information 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. > > > > 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). > > > > The patch contains the following improvements over the previous version: > > 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. > > > > [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 > > > > Signed-off-by: Hridya Valsaraju <hridya@xxxxxxxxxx> > > --- > > 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 attaching 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 ++++ > > drivers/dma-buf/Kconfig | 11 + > > drivers/dma-buf/Makefile | 1 + > > drivers/dma-buf/dma-buf-sysfs-stats.c | 283 ++++++++++++++++++ > > drivers/dma-buf/dma-buf-sysfs-stats.h | 62 ++++ > > drivers/dma-buf/dma-buf.c | 37 +++ > > include/linux/dma-buf.h | 20 ++ > > 7 files changed, 466 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..6f7c65209f07 > > --- /dev/null > > +++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers > > @@ -0,0 +1,52 @@ > > +What: /sys/kernel/dmabuf/buffers > > +Date: January 2021 > > +KernelVersion: v5.12 > > +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: January 2021 > > +KernelVersion: v5.12 > > +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: January 2021 > > +KernelVersion: v5.12 > > +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: January 2021 > > +KernelVersion: v5.12 > > +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: January 2021 > > +KernelVersion: v5.12 > > +Contact: Hridya Valsaraju <hridya@xxxxxxxxxx> > > +Description: This directory will contain information on the attaching device > > + and the number of current distinct device mappings. > > + > > +What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/device > > +Date: January 2021 > > +KernelVersion: v5.12 > > +Contact: Hridya Valsaraju <hridya@xxxxxxxxxx> > > +Description: This file is read-only and is a symlink to the attaching devices's > > + sysfs entry. > > + > > +What: /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/map_counter > > +Date: January 2021 > > +KernelVersion: v5.12 > > +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/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > > index 4f8224a6ac95..27e6a2dafeaa 100644 > > --- a/drivers/dma-buf/Kconfig > > +++ b/drivers/dma-buf/Kconfig > > @@ -64,6 +64,17 @@ 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..61f85c3d16a5 > > --- /dev/null > > +++ b/drivers/dma-buf/dma-buf-sysfs-stats.c > > @@ -0,0 +1,283 @@ > > +// 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> > > + > > +#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); > > +} > > + > > +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", NULL, kernel_kobj); > > + if (!dma_buf_stats_kset) > > + return -ENOMEM; > > + > > + dma_buf_per_buffer_stats_kset = kset_create_and_add("buffers", NULL, > > + &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", NULL, > > + &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 9ad6397aaa97..29f9ea18eb47 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); > > @@ -579,6 +582,10 @@ 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); > > > > @@ -588,6 +595,14 @@ 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: > > @@ -692,6 +707,7 @@ 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); > > @@ -717,8 +733,13 @@ 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. > > @@ -745,6 +766,7 @@ 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; > > @@ -761,6 +783,7 @@ 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); > > } > > @@ -799,6 +822,7 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) > > dma_resv_lock(attach->dmabuf->resv, NULL); > > > > dmabuf->ops->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); > > @@ -812,6 +836,7 @@ 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); > > @@ -938,6 +963,9 @@ 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); > > @@ -975,6 +1003,8 @@ 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); > > > > @@ -1412,6 +1442,12 @@ 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); > > @@ -1427,5 +1463,6 @@ 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 cf72699cb2bc..4ae5cc38a4a7 100644 > > --- a/include/linux/dma-buf.h > > +++ b/include/linux/dma-buf.h > > @@ -294,6 +294,9 @@ 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 > > @@ -329,6 +332,15 @@ 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 > > Why not directly embed that? Thank you for the review Christian! Kobjects need to act as reference counters to the objects they are embedded in. Since ref-counting for struct dma_buf is already handled by its 'file' member, we cannot embed the kobject directly into struct dma_buf. > > > }; > > > > /** > > @@ -378,6 +390,7 @@ 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 > > @@ -398,6 +411,13 @@ 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 > > Same question here. It is not directly embedded into struct dma_buf_attachment for the same reason as above since I do not think that it is correct to have the kobject act as reference count for struct dma_buf_attachment. Thanks again for all the reviews! Regards, Hridya > > Apart from that the general approach looks solid to me now. > > But somebody with more sysfs background should check if everything there > is the right thing to do. > > Regards, > Christian. > > > > > }; > > > > /**
