On Wed, May 26, 2021 at 7:01 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > On Wed, May 26, 2021 at 12:40:14PM +0200, Christian König wrote: > > Hi Hridya, > > > > Am 25.05.21 um 20:37 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. > > > > > > Procfs also uses the proc/<pid>/fdinfo/<fd> file to expose some > > > 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. > > > The sysfs interface also exposes attachment statistics for each buffer. > > > > > > 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 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. > > > > > > [1]: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fpatchwork%2Fpatch%2F1088791%2F&data=04%7C01%7Cchristian.koenig%40amd.com%7C72394dc653194a3fd3fd08d91fac2fb9%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637575646676575967%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=EJ8KluQVn8FTOYRBAYpxAaG7rua46eQpmGwI%2FxIMthQ%3D&reserved=0 > > > [2]: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fandroid-review.googlesource.com%2Fq%2Ftopic%3A%2522dmabuf-sysfs%2522&data=04%7C01%7Cchristian.koenig%40amd.com%7C72394dc653194a3fd3fd08d91fac2fb9%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637575646676575967%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=4sAAqK%2F6mtSr5MWpcu2EbwOvL93UA6kMwQ2uk4fMP1g%3D&reserved=0+(status:open%20OR%20status:merged) > > > [3]: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fandroid-review.googlesource.com%2Fc%2Fplatform%2Fsystem%2Fmemory%2Flibmeminfo%2F%2B%2F1549734&data=04%7C01%7Cchristian.koenig%40amd.com%7C72394dc653194a3fd3fd08d91fac2fb9%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637575646676575967%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hs40%2FMAnJaZQA4pkYucGqeCOGk2A9dUU%2Fj9ajqAoyFk%3D&reserved=0 > > > > > > Signed-off-by: Hridya Valsaraju <hridya@xxxxxxxxxx> > > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > --- > > > > > > Hi Daniel, > > > > > > I am sending the latest version of the DMA-BUF sysfs statistics patch to > > > the list again as per your suggestion to restart the discussion on it :) > > > Please do take a look and let me know your thoughts, thank you! > > > > Daniel and Sumit might correct me, but I think in the previous discussion we > > came pretty much to the conclusion that this is not the right approach. Sorry about the confusion Christian. I should have added a brief summary of our meeting with Daniel as well to provide further context. > > > > DMA-buf is just the transport vehicle for driver allocations and as Daniel > > outlined it doesn't really make sense to account on a DMA-buf level except > > for debugging. > > > > So while this patch is technically correct it will only add another halve > > backed uAPI. So question is rather what the alternative should look like? > > So I chatted a bit with Android folks in a quick meeting, and the rough > conclusions we've had was > > - for per-process stats we'll look into cgroups for tracking this (because > Android will add matching cgroup for each app the want to track) > > - same for the tracking for OOM killer > > - that does leave them with a gap for shared processes, for which I agreed > that just exposing the per dma-buf info is reasonable. It's not going to > be super useful on desktop linux because the dma-buf tends to not stick > around much, but it fits fairly perfectly on Android. > > So yeah that's why I think this is ok to have. > > What's missing is explaining this properly in the commit message. The > commit message explains nicely what's being added (which really should be > proper uapi docs in our Documentation/ files, not hidden in a commit > message where it's forgotten). But it fails to explain a bit the reasons > why we need this, I think a short summary of what Android needs (in an > abstract sense ie. high level semantics, not the specific implementation) > and why this fits and there's nothing better is needed here I think. Thank you Daniel, let me rewrite the commit message to explain this in a better manner and send out another patch set. The patch does add the ABI documentation in Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers. Is the suggestion to add them in a different location? > > > Both AMD and Intel engineers are currently discussion a fdinfo based > > approach on the dri-devel mailing list. > > > > I strongly suggest that you join this discussion as well (and sorry I don't > > have the link at hand). > > Yeah I think since Android keeps the dma-buf fd around anyway (by design), > and since this is geared 100% for Android, implementing this exact > functionality as an fdinfo on the dma-buf sounds a lot cleaner to me. > Putting this in sysfs is really a bit a hack. The /proc/<pid>/fdinfo/<fd> interface can only provide information about the buffers for which processes hold fds. Hence, for the purposes of calculating per-buffer statistics, parsing /proc/<pid>/fdinfo/<fd> by itself would not provide a complete picture. Thank you for the reviews and comments Greg, Christian and Daniel! Regards, Hridya > > But it is also orthogonal to our fdinfo discussion, since our fdinfo is > for the drm_file, not the dma-buf fd. > > Except ofc I'm yet again not quite understanding what exactly Android > wants/needs. > -Daniel > > > > > Regards, > > Christian. > > > > > > > > Regards, > > > Hridya > > > > > > 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 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 | 300 ++++++++++++++++++ > > > 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, 483 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..73a8c372b0f2 > > > --- /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 attaching 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 attaching devices'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/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 > > > }; > > > /** > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
