@@ -22,3 +22,17 @@ KernelVersion: v5.13
Contact: Hridya Valsaraju <hridya@google.com>
Description: This file is read-only and specifies the size of the DMA-BUF in
bytes.
+
+What: /sys/kernel/dmabuf/caps
+Date: May 2022
+KernelVersion: v5.19
+Contact: Simon Ser <contact@emersion.fr>
+Description: This directory advertises DMA-BUF capabilities supported by the
+ kernel.
+
+What: /sys/kernel/dmabuf/caps/sync_file_import_export
+Date: May 2022
+KernelVersion: v5.19
+Contact: Simon Ser <contact@emersion.fr>
+Description: This file is read-only and advertises support for importing and
+ exporting sync_files from/to DMA-BUFs.
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-y := dma-buf.o dma-fence.o dma-fence-array.o dma-fence-chain.o \
- dma-resv.o
+ dma-resv.o dma-buf-sysfs-caps.o
obj-$(CONFIG_DMABUF_HEAPS) += dma-heap.o
obj-$(CONFIG_DMABUF_HEAPS) += heaps/
obj-$(CONFIG_SYNC_FILE) += sync_file.o
@@ -141,21 +141,13 @@ 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)
+int dma_buf_init_sysfs_statistics(struct kset *kset)
{
- 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);
+ &kset->kobj);
if (!dma_buf_per_buffer_stats_kset) {
- kset_unregister(dma_buf_stats_kset);
return -ENOMEM;
}
@@ -165,7 +157,6 @@ int dma_buf_init_sysfs_statistics(void)
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)
@@ -8,9 +8,11 @@
#ifndef _DMA_BUF_SYSFS_STATS_H
#define _DMA_BUF_SYSFS_STATS_H
+struct kset;
+
#ifdef CONFIG_DMABUF_SYSFS_STATS
-int dma_buf_init_sysfs_statistics(void);
+int dma_buf_init_sysfs_statistics(struct kset *kset);
void dma_buf_uninit_sysfs_statistics(void);
int dma_buf_stats_setup(struct dma_buf *dmabuf);
@@ -18,7 +20,7 @@ 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)
+static inline int dma_buf_init_sysfs_statistics(struct kset *kset)
{
return 0;
}
@@ -30,6 +30,7 @@
#include <uapi/linux/dma-buf.h>
#include <uapi/linux/magic.h>
+#include "dma-buf-sysfs-caps.h"
#include "dma-buf-sysfs-stats.h"
static inline int is_dma_buf_file(struct file *);
@@ -1546,22 +1547,54 @@ static inline void dma_buf_uninit_debugfs(void)
}
#endif
+/* Capabilities and statistics files do not need to send uevents. */
+static int dmabuf_sysfs_uevent_filter(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_kset;
+
static int __init dma_buf_init(void)
{
int ret;
- ret = dma_buf_init_sysfs_statistics();
+ dma_buf_kset = kset_create_and_add("dmabuf",
+ &dmabuf_sysfs_no_uevent_ops,
+ kernel_kobj);
+ if (!dma_buf_kset)
+ return -ENOMEM;
+
+ ret = dma_buf_init_sysfs_capabilities(dma_buf_kset);
if (ret)
- return ret;
+ goto err_kset;
+
+ ret = dma_buf_init_sysfs_statistics(dma_buf_kset);
+ if (ret)
+ goto err_sysfs_caps;
dma_buf_mnt = kern_mount(&dma_buf_fs_type);
- if (IS_ERR(dma_buf_mnt))
- return PTR_ERR(dma_buf_mnt);
+ if (IS_ERR(dma_buf_mnt)) {
+ ret = PTR_ERR(dma_buf_mnt);
+ goto err_sysfs_stats;
+ }
mutex_init(&db_list.lock);
INIT_LIST_HEAD(&db_list.head);
dma_buf_init_debugfs();
return 0;
+
+err_sysfs_stats:
+ dma_buf_uninit_sysfs_statistics();
+err_sysfs_caps:
+ dma_buf_uninit_sysfs_capabilities();
+err_kset:
+ kset_unregister(dma_buf_kset);
+ return ret;
}
subsys_initcall(dma_buf_init);
@@ -1570,5 +1603,7 @@ static void __exit dma_buf_deinit(void)
dma_buf_uninit_debugfs();
kern_unmount(dma_buf_mnt);
dma_buf_uninit_sysfs_statistics();
+ dma_buf_uninit_sysfs_capabilities();
+ kset_unregister(dma_buf_kset);
}
__exitcall(dma_buf_deinit);
@@ -114,6 +114,9 @@ struct dma_buf_sync {
* ordering via these fences, it is the respnosibility of userspace to use
* locks or other mechanisms to ensure that no other context adds fences or
* submits work between steps 1 and 3 above.
+ *
+ * Userspace can check the availability of this API via
+ * /sys/kernel/dmabuf/caps/sync_file_import_export.
*/
struct dma_buf_export_sync_file {
/**
@@ -146,6 +149,9 @@ struct dma_buf_export_sync_file {
* synchronized APIs such as Vulkan to inter-op with dma-buf consumers
* which expect implicit synchronization such as OpenGL or most media
* drivers/video.
+ *
+ * Userspace can check the availability of this API via
+ * /sys/kernel/dmabuf/caps/sync_file_import_export.
*/
struct dma_buf_import_sync_file {
/**
To discover support for new DMA-BUF IOCTLs, user-space has no choice but to try to perform the IOCTL on an existing DMA-BUF. However, user-space may want to figure out whether or not the IOCTL is available before it has a DMA-BUF at hand, e.g. at initialization time in a Wayland compositor. Add a /sys/kernel/dmabuf/caps directory which allows the DMA-BUF subsystem to advertise supported features. Add a sync_file_import_export entry which indicates that importing and exporting sync_files from/to DMA-BUFs is supported. Signed-off-by: Simon Ser <contact@emersion.fr> Cc: Jason Ekstrand <jason@jlekstrand.net> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Cc: Christian König <christian.koenig@amd.com> --- This depends on: https://patchwork.freedesktop.org/series/103715/ .../ABI/testing/sysfs-kernel-dmabuf-buffers | 14 ++++++ drivers/dma-buf/Makefile | 2 +- drivers/dma-buf/dma-buf-sysfs-stats.c | 13 +----- drivers/dma-buf/dma-buf-sysfs-stats.h | 6 ++- drivers/dma-buf/dma-buf.c | 43 +++++++++++++++++-- include/uapi/linux/dma-buf.h | 6 +++ 6 files changed, 66 insertions(+), 18 deletions(-)