diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers new file mode 100644 index 0000000000000000000000000000000000000000..5d3bc997dc6400138012854521044793bc380f0c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers @@ -0,0 +1,24 @@ +What: /sys/kernel/dmabuf/buffers +Date: May 2021 +KernelVersion: v5.13 +Contact: Hridya Valsaraju +Description: The /sys/kernel/dmabuf/buffers directory contains a + snapshot of the internal state of every DMA-BUF. + /sys/kernel/dmabuf/buffers/ will contain the + statistics for the DMA-BUF with the unique inode number + +Users: kernel memory tuning/debugging tools + +What: /sys/kernel/dmabuf/buffers//exporter_name +Date: May 2021 +KernelVersion: v5.13 +Contact: Hridya Valsaraju +Description: This file is read-only and contains the name of the exporter of + the DMA-BUF. + +What: /sys/kernel/dmabuf/buffers//size +Date: May 2021 +KernelVersion: v5.13 +Contact: Hridya Valsaraju +Description: This file is read-only and specifies the size of the DMA-BUF in + bytes. diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index 4144b669e80c14b3c15bcbfae367da205fc7ba85..38ba0a3ec4b350663361ff3db9966351f606eaae 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 3ca7de37dd8f236a590f6bc3ef5d3ee08bbdb294..3280ca972502f486edfc84a8ca9524c8b75e5306 100644 --- a/drivers/dma-buf/Kconfig +++ b/drivers/dma-buf/Kconfig @@ -65,6 +65,17 @@ menuconfig DMABUF_HEAPS allows userspace to allocate dma-bufs that can be shared between drivers. +menuconfig DMABUF_SYSFS_STATS + bool "DMA-BUF sysfs statistics" + depends on DMA_SHARED_BUFFER + help + Choose this option to enable DMA-BUF sysfs statistics + in location /sys/kernel/dmabuf/buffers. + + /sys/kernel/dmabuf/buffers/ will contain + statistics for the DMA-BUF with the unique inode number + . + source "drivers/dma-buf/heaps/Kconfig" endmenu diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile index 995e05f609ff0b549026cb33d465e210aa174f24..40d81f23cacfec93637e6b973eac354abbe9855e 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 0000000000000000000000000000000000000000..053baadcada9466e863d028f01e4e97f108aac7c --- /dev/null +++ b/drivers/dma-buf/dma-buf-sysfs-stats.c @@ -0,0 +1,205 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * DMA-BUF sysfs statistics. + * + * Copyright (C) 2021 Google LLC. + */ + +#include +#include +#include +#include +#include +#include + +#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//fdinfo/`` 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//exporter_name`` + * * ``/sys/kernel/dmabuf/buffers//size`` + * + * The information in the interface can also be used to derive per-exporter + * statistics. The data from the interface can be gathered on error conditions + * or other important events to provide a snapshot of DMA-BUF usage. + * It can also be collected periodically by telemetry to monitor various metrics. + * + * Detailed documentation about the interface is present in + * Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers. + */ + +struct dma_buf_stats_attribute { + struct attribute attr; + ssize_t (*show)(struct dma_buf *dmabuf, + struct dma_buf_stats_attribute *attr, char *buf); +}; +#define to_dma_buf_stats_attr(x) container_of(x, struct dma_buf_stats_attribute, attr) + +static ssize_t dma_buf_stats_attribute_show(struct kobject *kobj, + struct attribute *attr, + char *buf) +{ + struct dma_buf_stats_attribute *attribute; + struct dma_buf_sysfs_entry *sysfs_entry; + struct dma_buf *dmabuf; + + attribute = to_dma_buf_stats_attr(attr); + sysfs_entry = to_dma_buf_entry_from_kobj(kobj); + dmabuf = sysfs_entry->dmabuf; + + if (!dmabuf || !attribute->show) + return -EIO; + + return attribute->show(dmabuf, attribute, buf); +} + +static const struct sysfs_ops dma_buf_stats_sysfs_ops = { + .show = dma_buf_stats_attribute_show, +}; + +static ssize_t exporter_name_show(struct dma_buf *dmabuf, + struct dma_buf_stats_attribute *attr, + char *buf) +{ + return sysfs_emit(buf, "%s\n", dmabuf->exp_name); +} + +static ssize_t size_show(struct dma_buf *dmabuf, + struct dma_buf_stats_attribute *attr, + char *buf) +{ + return sysfs_emit(buf, "%zu\n", dmabuf->size); +} + +static struct dma_buf_stats_attribute exporter_name_attribute = + __ATTR_RO(exporter_name); +static struct dma_buf_stats_attribute size_attribute = __ATTR_RO(size); + +static struct attribute *dma_buf_stats_default_attrs[] = { + &exporter_name_attribute.attr, + &size_attribute.attr, + NULL, +}; +ATTRIBUTE_GROUPS(dma_buf_stats_default); + +static void dma_buf_sysfs_release(struct kobject *kobj) +{ + struct dma_buf_sysfs_entry *sysfs_entry; + + sysfs_entry = to_dma_buf_entry_from_kobj(kobj); + kfree(sysfs_entry); +} + +static struct kobj_type dma_buf_ktype = { + .sysfs_ops = &dma_buf_stats_sysfs_ops, + .release = dma_buf_sysfs_release, + .default_groups = dma_buf_stats_default_groups, +}; + +void dma_buf_stats_teardown(struct dma_buf *dmabuf) +{ + struct dma_buf_sysfs_entry *sysfs_entry; + + sysfs_entry = dmabuf->sysfs_entry; + if (!sysfs_entry) + return; + + kobject_del(&sysfs_entry->kobj); + kobject_put(&sysfs_entry->kobj); +} + + +/* Statistics files do not need to send uevents. */ +static int dmabuf_sysfs_uevent_filter(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; + + 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; + + return 0; + +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 0000000000000000000000000000000000000000..a49c6e2650cccddb5eddf639bca14df89a36050b --- /dev/null +++ b/drivers/dma-buf/dma-buf-sysfs-stats.h @@ -0,0 +1,35 @@ +/* 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); + +void dma_buf_stats_teardown(struct dma_buf *dmabuf); +#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 void dma_buf_stats_teardown(struct dma_buf *dmabuf) {} +#endif +#endif // _DMA_BUF_SYSFS_STATS_H diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 922416b3aaceba1eb56d08e8d2c9ed9c142417e7..f55396de2fcc4f7f9e51d446007b5e3026267f62 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -29,6 +29,8 @@ #include #include +#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: @@ -1402,6 +1417,12 @@ 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); @@ -1417,5 +1438,6 @@ 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/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index afd22c9dbdcfa16864f07e2fdab2e1ed8f5992fb..70e410c64c1c8bfbb98001687713d01a8f602b79 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -190,6 +190,18 @@ void *dma_heap_get_drvdata(struct dma_heap *heap) return heap->priv; } +/** + * dma_heap_get_name() - get heap name + * @heap: DMA-Heap to retrieve private data for + * + * Returns: + * The char* for the heap name. + */ +const char *dma_heap_get_name(struct dma_heap *heap) +{ + return heap->name; +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c index d0696cf937af3476578bac4a10464e8948720545..35aa65bbf0a778b21e439e134da37f83ba1f39c9 100644 --- a/drivers/dma-buf/heaps/heap-helpers.c +++ b/drivers/dma-buf/heaps/heap-helpers.c @@ -30,6 +30,7 @@ struct dma_buf *heap_helper_export_dmabuf(struct heap_helper_buffer *buffer, { DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + exp_info.exp_name = dma_heap_get_name(buffer->heap); exp_info.ops = &heap_helper_ops; exp_info.size = buffer->size; exp_info.flags = fd_flags; diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 957b398d30e5d88959c3374157689b5c6b412803..e79fa6751fe09d68c7d15e3177d10ed89d0c519f 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -292,6 +292,9 @@ 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 @@ -327,6 +330,13 @@ 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; + } *sysfs_entry; +#endif }; /** diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 454e354d1ffb7e10ab62bafe36d147b58d56aba9..83b8cfb2d760f60acef00ab080a535cd9d868e65 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -50,6 +50,15 @@ struct dma_heap_export_info { */ void *dma_heap_get_drvdata(struct dma_heap *heap); +/** + * dma_heap_get_name() - get heap name + * @heap: DMA-Heap to retrieve private data for + * + * Returns: + * The char* for the heap name. + */ +const char *dma_heap_get_name(struct dma_heap *heap); + /** * dma_heap_add - adds a heap to dmabuf heaps * @exp_info: information needed to register this heap