* [PATCH v3] dma-buf: Add a capabilities directory
@ 2022-05-27 7:34 Simon Ser
2022-05-30 7:09 ` Christian König
0 siblings, 1 reply; 8+ messages in thread
From: Simon Ser @ 2022-05-27 7:34 UTC (permalink / raw)
To: dri-devel; +Cc: Jason Ekstrand, Greg KH, Christian König, Daniel Vetter
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.
v2: Add missing files lost in a rebase
v3:
- Create separate file in Documentation/ABI/testing/, add it to
MAINTAINERS
- Fix kernel version (Daniel)
- Remove unnecessary brackets (Jason)
- Fix SPDX comment style
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Cc: Christian König <christian.koenig@amd.com>
Cc: Greg KH <greg@kroah.com>
---
.../ABI/testing/sysfs-kernel-dmabuf-caps | 13 +++++
MAINTAINERS | 1 +
drivers/dma-buf/Makefile | 2 +-
drivers/dma-buf/dma-buf-sysfs-caps.c | 51 +++++++++++++++++++
drivers/dma-buf/dma-buf-sysfs-caps.h | 16 ++++++
drivers/dma-buf/dma-buf-sysfs-stats.c | 16 ++----
drivers/dma-buf/dma-buf-sysfs-stats.h | 6 ++-
drivers/dma-buf/dma-buf.c | 43 ++++++++++++++--
include/uapi/linux/dma-buf.h | 6 +++
9 files changed, 134 insertions(+), 20 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.c
create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.h
diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
new file mode 100644
index 000000000000..f83af422fd18
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
@@ -0,0 +1,13 @@
+What: /sys/kernel/dmabuf/caps
+Date: May 2022
+KernelVersion: v5.20
+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: v5.20
+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.
diff --git a/MAINTAINERS b/MAINTAINERS
index 11da16bfa123..8966686f7231 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5871,6 +5871,7 @@ L: dri-devel@lists.freedesktop.org
L: linaro-mm-sig@lists.linaro.org (moderated for non-subscribers)
S: Maintained
T: git git://anongit.freedesktop.org/drm/drm-misc
+F: Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
F: Documentation/driver-api/dma-buf.rst
F: drivers/dma-buf/
F: include/linux/*fence.h
diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
index 4c9eb53ba3f8..afc874272710 100644
--- a/drivers/dma-buf/Makefile
+++ b/drivers/dma-buf/Makefile
@@ -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
diff --git a/drivers/dma-buf/dma-buf-sysfs-caps.c b/drivers/dma-buf/dma-buf-sysfs-caps.c
new file mode 100644
index 000000000000..82b91eb874a9
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-sysfs-caps.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DMA-BUF sysfs capabilities.
+ *
+ * Copyright (C) 2022 Simon Ser
+ */
+
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+
+#include "dma-buf-sysfs-caps.h"
+
+static ssize_t sync_file_import_export_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sysfs_emit(buf, "1\n");
+}
+
+static struct kobj_attribute dma_buf_sync_file_import_export_attr =
+ __ATTR_RO(sync_file_import_export);
+
+static struct attribute *dma_buf_caps_attrs[] = {
+ &dma_buf_sync_file_import_export_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group dma_buf_caps_attr_group = {
+ .attrs = dma_buf_caps_attrs,
+};
+
+static struct kobject *dma_buf_caps_kobj;
+
+int dma_buf_init_sysfs_capabilities(struct kset *kset)
+{
+ int ret;
+
+ dma_buf_caps_kobj = kobject_create_and_add("caps", &kset->kobj);
+ if (!dma_buf_caps_kobj)
+ return -ENOMEM;
+
+ ret = sysfs_create_group(dma_buf_caps_kobj, &dma_buf_caps_attr_group);
+ if (ret)
+ kobject_put(dma_buf_caps_kobj);
+ return ret;
+}
+
+void dma_buf_uninit_sysfs_capabilities(void)
+{
+ kobject_put(dma_buf_caps_kobj);
+}
diff --git a/drivers/dma-buf/dma-buf-sysfs-caps.h b/drivers/dma-buf/dma-buf-sysfs-caps.h
new file mode 100644
index 000000000000..d7bcef490b31
--- /dev/null
+++ b/drivers/dma-buf/dma-buf-sysfs-caps.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * DMA-BUF sysfs capabilities.
+ *
+ * Copyright (C) 2022 Simon Ser
+ */
+
+#ifndef _DMA_BUF_SYSFS_CAPS_H
+#define _DMA_BUF_SYSFS_CAPS_H
+
+struct kset;
+
+int dma_buf_init_sysfs_capabilities(struct kset *kset);
+void dma_buf_uninit_sysfs_capabilities(void);
+
+#endif // _DMA_BUF_SYSFS_CAPS_H
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
index 2bba0babcb62..e2e62f83ce18 100644
--- a/drivers/dma-buf/dma-buf-sysfs-stats.c
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
@@ -141,23 +141,14 @@ 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);
- if (!dma_buf_per_buffer_stats_kset) {
- kset_unregister(dma_buf_stats_kset);
+ &kset->kobj);
+ if (!dma_buf_per_buffer_stats_kset)
return -ENOMEM;
- }
return 0;
}
@@ -165,7 +156,6 @@ 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)
diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
index a49c6e2650cc..798c54fb8ee3 100644
--- a/drivers/dma-buf/dma-buf-sysfs-stats.h
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
@@ -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;
}
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 5e1b0534b3ce..b5c5a5050508 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -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);
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
index 70e213a0d7d9..ab3afd5da75a 100644
--- a/include/uapi/linux/dma-buf.h
+++ b/include/uapi/linux/dma-buf.h
@@ -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 {
/**
--
2.36.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-27 7:34 [PATCH v3] dma-buf: Add a capabilities directory Simon Ser
@ 2022-05-30 7:09 ` Christian König
2022-05-30 7:20 ` Greg KH
2022-05-30 7:55 ` Simon Ser
0 siblings, 2 replies; 8+ messages in thread
From: Christian König @ 2022-05-30 7:09 UTC (permalink / raw)
To: Simon Ser, dri-devel; +Cc: Jason Ekstrand, Greg KH, Daniel Vetter
Am 27.05.22 um 09:34 schrieb Simon Ser:
> 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.
I find a separate directory rather unusual, but can't come up with any
better idea either.
IIRC the security module had a mask file with names for the supported
capabilities.
>
> v2: Add missing files lost in a rebase
>
> v3:
> - Create separate file in Documentation/ABI/testing/, add it to
> MAINTAINERS
> - Fix kernel version (Daniel)
> - Remove unnecessary brackets (Jason)
> - Fix SPDX comment style
>
> Signed-off-by: Simon Ser <contact@emersion.fr>
> Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Greg KH <greg@kroah.com>
> ---
> .../ABI/testing/sysfs-kernel-dmabuf-caps | 13 +++++
> MAINTAINERS | 1 +
> drivers/dma-buf/Makefile | 2 +-
> drivers/dma-buf/dma-buf-sysfs-caps.c | 51 +++++++++++++++++++
> drivers/dma-buf/dma-buf-sysfs-caps.h | 16 ++++++
> drivers/dma-buf/dma-buf-sysfs-stats.c | 16 ++----
> drivers/dma-buf/dma-buf-sysfs-stats.h | 6 ++-
> drivers/dma-buf/dma-buf.c | 43 ++++++++++++++--
> include/uapi/linux/dma-buf.h | 6 +++
> 9 files changed, 134 insertions(+), 20 deletions(-)
> create mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.c
> create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.h
>
> diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> new file mode 100644
> index 000000000000..f83af422fd18
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> @@ -0,0 +1,13 @@
> +What: /sys/kernel/dmabuf/caps
> +Date: May 2022
> +KernelVersion: v5.20
> +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: v5.20
> +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.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 11da16bfa123..8966686f7231 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5871,6 +5871,7 @@ L: dri-devel@lists.freedesktop.org
> L: linaro-mm-sig@lists.linaro.org (moderated for non-subscribers)
> S: Maintained
> T: git git://anongit.freedesktop.org/drm/drm-misc
> +F: Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> F: Documentation/driver-api/dma-buf.rst
> F: drivers/dma-buf/
> F: include/linux/*fence.h
> diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> index 4c9eb53ba3f8..afc874272710 100644
> --- a/drivers/dma-buf/Makefile
> +++ b/drivers/dma-buf/Makefile
> @@ -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
> diff --git a/drivers/dma-buf/dma-buf-sysfs-caps.c b/drivers/dma-buf/dma-buf-sysfs-caps.c
> new file mode 100644
> index 000000000000..82b91eb874a9
> --- /dev/null
> +++ b/drivers/dma-buf/dma-buf-sysfs-caps.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * DMA-BUF sysfs capabilities.
> + *
> + * Copyright (C) 2022 Simon Ser
> + */
> +
> +#include <linux/kobject.h>
> +#include <linux/sysfs.h>
> +
> +#include "dma-buf-sysfs-caps.h"
> +
> +static ssize_t sync_file_import_export_show(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + char *buf)
> +{
> + return sysfs_emit(buf, "1\n");
> +}
> +
> +static struct kobj_attribute dma_buf_sync_file_import_export_attr =
> + __ATTR_RO(sync_file_import_export);
> +
> +static struct attribute *dma_buf_caps_attrs[] = {
> + &dma_buf_sync_file_import_export_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group dma_buf_caps_attr_group = {
> + .attrs = dma_buf_caps_attrs,
> +};
Didn't we had macros for those? I think I have seen something for that.
Apart from those two random thoughts looks good to me as well.
Regards,
Christian.
> +
> +static struct kobject *dma_buf_caps_kobj;
> +
> +int dma_buf_init_sysfs_capabilities(struct kset *kset)
> +{
> + int ret;
> +
> + dma_buf_caps_kobj = kobject_create_and_add("caps", &kset->kobj);
> + if (!dma_buf_caps_kobj)
> + return -ENOMEM;
> +
> + ret = sysfs_create_group(dma_buf_caps_kobj, &dma_buf_caps_attr_group);
> + if (ret)
> + kobject_put(dma_buf_caps_kobj);
> + return ret;
> +}
> +
> +void dma_buf_uninit_sysfs_capabilities(void)
> +{
> + kobject_put(dma_buf_caps_kobj);
> +}
> diff --git a/drivers/dma-buf/dma-buf-sysfs-caps.h b/drivers/dma-buf/dma-buf-sysfs-caps.h
> new file mode 100644
> index 000000000000..d7bcef490b31
> --- /dev/null
> +++ b/drivers/dma-buf/dma-buf-sysfs-caps.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * DMA-BUF sysfs capabilities.
> + *
> + * Copyright (C) 2022 Simon Ser
> + */
> +
> +#ifndef _DMA_BUF_SYSFS_CAPS_H
> +#define _DMA_BUF_SYSFS_CAPS_H
> +
> +struct kset;
> +
> +int dma_buf_init_sysfs_capabilities(struct kset *kset);
> +void dma_buf_uninit_sysfs_capabilities(void);
> +
> +#endif // _DMA_BUF_SYSFS_CAPS_H
> diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
> index 2bba0babcb62..e2e62f83ce18 100644
> --- a/drivers/dma-buf/dma-buf-sysfs-stats.c
> +++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
> @@ -141,23 +141,14 @@ 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);
> - if (!dma_buf_per_buffer_stats_kset) {
> - kset_unregister(dma_buf_stats_kset);
> + &kset->kobj);
> + if (!dma_buf_per_buffer_stats_kset)
> return -ENOMEM;
> - }
>
> return 0;
> }
> @@ -165,7 +156,6 @@ 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)
> diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
> index a49c6e2650cc..798c54fb8ee3 100644
> --- a/drivers/dma-buf/dma-buf-sysfs-stats.h
> +++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
> @@ -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;
> }
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 5e1b0534b3ce..b5c5a5050508 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -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);
> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> index 70e213a0d7d9..ab3afd5da75a 100644
> --- a/include/uapi/linux/dma-buf.h
> +++ b/include/uapi/linux/dma-buf.h
> @@ -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 {
> /**
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-30 7:09 ` Christian König
@ 2022-05-30 7:20 ` Greg KH
2022-05-30 8:15 ` Simon Ser
2022-05-30 7:55 ` Simon Ser
1 sibling, 1 reply; 8+ messages in thread
From: Greg KH @ 2022-05-30 7:20 UTC (permalink / raw)
To: Christian König, Simon Ser; +Cc: Jason Ekstrand, dri-devel, Daniel Vetter
On Mon, May 30, 2022 at 09:09:30AM +0200, Christian König wrote:
> Am 27.05.22 um 09:34 schrieb Simon Ser:
> > 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.
>
> I find a separate directory rather unusual, but can't come up with any
> better idea either.
>
> IIRC the security module had a mask file with names for the supported
> capabilities.
>
> >
> > v2: Add missing files lost in a rebase
> >
> > v3:
> > - Create separate file in Documentation/ABI/testing/, add it to
> > MAINTAINERS
> > - Fix kernel version (Daniel)
> > - Remove unnecessary brackets (Jason)
> > - Fix SPDX comment style
> >
> > Signed-off-by: Simon Ser <contact@emersion.fr>
> > Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
> > Cc: Christian König <christian.koenig@amd.com>
> > Cc: Greg KH <greg@kroah.com>
> > ---
> > .../ABI/testing/sysfs-kernel-dmabuf-caps | 13 +++++
> > MAINTAINERS | 1 +
> > drivers/dma-buf/Makefile | 2 +-
> > drivers/dma-buf/dma-buf-sysfs-caps.c | 51 +++++++++++++++++++
> > drivers/dma-buf/dma-buf-sysfs-caps.h | 16 ++++++
> > drivers/dma-buf/dma-buf-sysfs-stats.c | 16 ++----
> > drivers/dma-buf/dma-buf-sysfs-stats.h | 6 ++-
> > drivers/dma-buf/dma-buf.c | 43 ++++++++++++++--
> > include/uapi/linux/dma-buf.h | 6 +++
> > 9 files changed, 134 insertions(+), 20 deletions(-)
> > create mode 100644 Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> > create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.c
> > create mode 100644 drivers/dma-buf/dma-buf-sysfs-caps.h
> >
> > diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> > new file mode 100644
> > index 000000000000..f83af422fd18
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> > @@ -0,0 +1,13 @@
> > +What: /sys/kernel/dmabuf/caps
> > +Date: May 2022
> > +KernelVersion: v5.20
> > +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: v5.20
> > +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.
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 11da16bfa123..8966686f7231 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -5871,6 +5871,7 @@ L: dri-devel@lists.freedesktop.org
> > L: linaro-mm-sig@lists.linaro.org (moderated for non-subscribers)
> > S: Maintained
> > T: git git://anongit.freedesktop.org/drm/drm-misc
> > +F: Documentation/ABI/testing/sysfs-kernel-dmabuf-caps
> > F: Documentation/driver-api/dma-buf.rst
> > F: drivers/dma-buf/
> > F: include/linux/*fence.h
> > diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile
> > index 4c9eb53ba3f8..afc874272710 100644
> > --- a/drivers/dma-buf/Makefile
> > +++ b/drivers/dma-buf/Makefile
> > @@ -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
> > diff --git a/drivers/dma-buf/dma-buf-sysfs-caps.c b/drivers/dma-buf/dma-buf-sysfs-caps.c
> > new file mode 100644
> > index 000000000000..82b91eb874a9
> > --- /dev/null
> > +++ b/drivers/dma-buf/dma-buf-sysfs-caps.c
> > @@ -0,0 +1,51 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * DMA-BUF sysfs capabilities.
> > + *
> > + * Copyright (C) 2022 Simon Ser
> > + */
> > +
> > +#include <linux/kobject.h>
> > +#include <linux/sysfs.h>
> > +
> > +#include "dma-buf-sysfs-caps.h"
> > +
> > +static ssize_t sync_file_import_export_show(struct kobject *kobj,
> > + struct kobj_attribute *attr,
> > + char *buf)
> > +{
> > + return sysfs_emit(buf, "1\n");
> > +}
> > +
> > +static struct kobj_attribute dma_buf_sync_file_import_export_attr =
> > + __ATTR_RO(sync_file_import_export);
> > +
> > +static struct attribute *dma_buf_caps_attrs[] = {
> > + &dma_buf_sync_file_import_export_attr.attr,
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group dma_buf_caps_attr_group = {
> > + .attrs = dma_buf_caps_attrs,
> > +};
>
> Didn't we had macros for those? I think I have seen something for that.
Yes, please use ATTRIBUTE_GROUPS()
> > +
> > +static struct kobject *dma_buf_caps_kobj;
> > +
> > +int dma_buf_init_sysfs_capabilities(struct kset *kset)
> > +{
> > + int ret;
> > +
> > + dma_buf_caps_kobj = kobject_create_and_add("caps", &kset->kobj);
> > + if (!dma_buf_caps_kobj)
> > + return -ENOMEM;
> > +
> > + ret = sysfs_create_group(dma_buf_caps_kobj, &dma_buf_caps_attr_group);
Why do we have "raw" kobjects here?
A group can have a name, which puts it in the subdirectory of the object
it is attached to. Please do that and do not create a new kobject.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-30 7:20 ` Greg KH
@ 2022-05-30 8:15 ` Simon Ser
2022-05-30 8:26 ` Greg KH
0 siblings, 1 reply; 8+ messages in thread
From: Simon Ser @ 2022-05-30 8:15 UTC (permalink / raw)
To: Greg KH; +Cc: Jason Ekstrand, Christian König, dri-devel, Daniel Vetter
On Monday, May 30th, 2022 at 09:20, Greg KH <gregkh@linuxfoundation.org> wrote:
> > > +static struct attribute *dma_buf_caps_attrs[] = {
> > > + &dma_buf_sync_file_import_export_attr.attr,
> > > + NULL,
> > > +};
> > > +
> > > +static const struct attribute_group dma_buf_caps_attr_group = {
> > > + .attrs = dma_buf_caps_attrs,
> > > +};
> >
> > Didn't we had macros for those? I think I have seen something for that.
>
> Yes, please use ATTRIBUTE_GROUPS()
This doesn't allow the user to set a group name, and creates an unused
"_groups" variable, causing warnings.
> > > +
> > > +static struct kobject *dma_buf_caps_kobj;
> > > +
> > > +int dma_buf_init_sysfs_capabilities(struct kset *kset)
> > > +{
> > > + int ret;
> > > +
> > > + dma_buf_caps_kobj = kobject_create_and_add("caps", &kset->kobj);
> > > + if (!dma_buf_caps_kobj)
> > > + return -ENOMEM;
> > > +
> > > + ret = sysfs_create_group(dma_buf_caps_kobj, &dma_buf_caps_attr_group);
>
> Why do we have "raw" kobjects here?
>
> A group can have a name, which puts it in the subdirectory of the object
> it is attached to. Please do that and do not create a new kobject.
I see, I'll switch to sysfs_create_group with a group name in the next version.
Thanks for the pointers!
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-30 8:15 ` Simon Ser
@ 2022-05-30 8:26 ` Greg KH
2022-05-31 12:53 ` Jason Ekstrand
0 siblings, 1 reply; 8+ messages in thread
From: Greg KH @ 2022-05-30 8:26 UTC (permalink / raw)
To: Simon Ser; +Cc: Jason Ekstrand, Christian König, dri-devel, Daniel Vetter
On Mon, May 30, 2022 at 08:15:04AM +0000, Simon Ser wrote:
> On Monday, May 30th, 2022 at 09:20, Greg KH <gregkh@linuxfoundation.org> wrote:
>
> > > > +static struct attribute *dma_buf_caps_attrs[] = {
> > > > + &dma_buf_sync_file_import_export_attr.attr,
> > > > + NULL,
> > > > +};
> > > > +
> > > > +static const struct attribute_group dma_buf_caps_attr_group = {
> > > > + .attrs = dma_buf_caps_attrs,
> > > > +};
> > >
> > > Didn't we had macros for those? I think I have seen something for that.
> >
> > Yes, please use ATTRIBUTE_GROUPS()
>
> This doesn't allow the user to set a group name, and creates an unused
> "_groups" variable, causing warnings.
Then set a group name.
But you really want to almost always be using lists of groups, which is
why that macro works that way.
>
> > > > +
> > > > +static struct kobject *dma_buf_caps_kobj;
> > > > +
> > > > +int dma_buf_init_sysfs_capabilities(struct kset *kset)
> > > > +{
> > > > + int ret;
> > > > +
> > > > + dma_buf_caps_kobj = kobject_create_and_add("caps", &kset->kobj);
> > > > + if (!dma_buf_caps_kobj)
> > > > + return -ENOMEM;
> > > > +
> > > > + ret = sysfs_create_group(dma_buf_caps_kobj, &dma_buf_caps_attr_group);
> >
> > Why do we have "raw" kobjects here?
> >
> > A group can have a name, which puts it in the subdirectory of the object
> > it is attached to. Please do that and do not create a new kobject.
>
> I see, I'll switch to sysfs_create_group with a group name in the next version.
No, do not do that, add it to the list of groups for the original
kobject.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-30 8:26 ` Greg KH
@ 2022-05-31 12:53 ` Jason Ekstrand
2022-05-31 18:37 ` Greg KH
0 siblings, 1 reply; 8+ messages in thread
From: Jason Ekstrand @ 2022-05-31 12:53 UTC (permalink / raw)
To: Greg KH, Simon Ser; +Cc: Daniel Vetter, Christian König, dri-devel
On Mon, 2022-05-30 at 10:26 +0200, Greg KH wrote:
> On Mon, May 30, 2022 at 08:15:04AM +0000, Simon Ser wrote:
> > On Monday, May 30th, 2022 at 09:20, Greg KH
> > <gregkh@linuxfoundation.org> wrote:
> >
> > > > > +static struct attribute *dma_buf_caps_attrs[] = {
> > > > > + &dma_buf_sync_file_import_export_attr.attr,
> > > > > + NULL,
> > > > > +};
> > > > > +
> > > > > +static const struct attribute_group dma_buf_caps_attr_group
> > > > > = {
> > > > > + .attrs = dma_buf_caps_attrs,
> > > > > +};
> > > >
> > > > Didn't we had macros for those? I think I have seen something
> > > > for that.
> > >
> > > Yes, please use ATTRIBUTE_GROUPS()
> >
> > This doesn't allow the user to set a group name, and creates an
> > unused
> > "_groups" variable, causing warnings.
>
> Then set a group name.
>
> But you really want to almost always be using lists of groups, which
> is
> why that macro works that way.
I think I see the confusion here. The ATTRIBUTE_GROUPS() macro is
intended for device drivers and to be used with add_device(). However,
this is dma-buf so there is no device and no add_device() call to hook.
Unless there are other magic macros to use in this case, I think we're
stuck doing it manually.
--Jason
> >
> > > > > +
> > > > > +static struct kobject *dma_buf_caps_kobj;
> > > > > +
> > > > > +int dma_buf_init_sysfs_capabilities(struct kset *kset)
> > > > > +{
> > > > > + int ret;
> > > > > +
> > > > > + dma_buf_caps_kobj = kobject_create_and_add("caps",
> > > > > &kset->kobj);
> > > > > + if (!dma_buf_caps_kobj)
> > > > > + return -ENOMEM;
> > > > > +
> > > > > + ret = sysfs_create_group(dma_buf_caps_kobj,
> > > > > &dma_buf_caps_attr_group);
> > >
> > > Why do we have "raw" kobjects here?
> > >
> > > A group can have a name, which puts it in the subdirectory of the
> > > object
> > > it is attached to. Please do that and do not create a new
> > > kobject.
> >
> > I see, I'll switch to sysfs_create_group with a group name in the
> > next version.
>
> No, do not do that, add it to the list of groups for the original
> kobject.
>
> thanks,
>
> greg k-h
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-31 12:53 ` Jason Ekstrand
@ 2022-05-31 18:37 ` Greg KH
0 siblings, 0 replies; 8+ messages in thread
From: Greg KH @ 2022-05-31 18:37 UTC (permalink / raw)
To: Jason Ekstrand; +Cc: Christian König, dri-devel, Daniel Vetter
On Tue, May 31, 2022 at 07:53:50AM -0500, Jason Ekstrand wrote:
> On Mon, 2022-05-30 at 10:26 +0200, Greg KH wrote:
> > On Mon, May 30, 2022 at 08:15:04AM +0000, Simon Ser wrote:
> > > On Monday, May 30th, 2022 at 09:20, Greg KH
> > > <gregkh@linuxfoundation.org> wrote:
> > >
> > > > > > +static struct attribute *dma_buf_caps_attrs[] = {
> > > > > > + &dma_buf_sync_file_import_export_attr.attr,
> > > > > > + NULL,
> > > > > > +};
> > > > > > +
> > > > > > +static const struct attribute_group dma_buf_caps_attr_group
> > > > > > = {
> > > > > > + .attrs = dma_buf_caps_attrs,
> > > > > > +};
> > > > >
> > > > > Didn't we had macros for those? I think I have seen something
> > > > > for that.
> > > >
> > > > Yes, please use ATTRIBUTE_GROUPS()
> > >
> > > This doesn't allow the user to set a group name, and creates an
> > > unused
> > > "_groups" variable, causing warnings.
> >
> > Then set a group name.
> >
> > But you really want to almost always be using lists of groups, which
> > is
> > why that macro works that way.
>
> I think I see the confusion here. The ATTRIBUTE_GROUPS() macro is
> intended for device drivers and to be used with add_device(). However,
> this is dma-buf so there is no device and no add_device() call to hook.
> Unless there are other magic macros to use in this case, I think we're
> stuck doing it manually.
Have a list of attribute groups and add it to the kobject when you
create it so they all get created at the same time.
Don't do piece-meal "add one, and then another, and then another" as
that just gets messy and complex and impossible to unwind the error
conditions from.
sysfs_create_groups() is what you need to use here. I need to drop
sysfs_create_group() one day...
thanks,
greg k-h
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3] dma-buf: Add a capabilities directory
2022-05-30 7:09 ` Christian König
2022-05-30 7:20 ` Greg KH
@ 2022-05-30 7:55 ` Simon Ser
1 sibling, 0 replies; 8+ messages in thread
From: Simon Ser @ 2022-05-30 7:55 UTC (permalink / raw)
To: Christian König; +Cc: Jason Ekstrand, Greg KH, dri-devel, Daniel Vetter
On Monday, May 30th, 2022 at 09:09, Christian König <christian.koenig@amd.com> wrote:
> I find a separate directory rather unusual, but can't come up with any
> better idea either.
>
> IIRC the security module had a mask file with names for the supported
> capabilities.
Are you referring to /sys/kernel/security/lsm?
This sounds more painful to parse from user-space. Instead of a simple
stat(), user-space would need to read the file, split on commas, and
compare strings.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-05-31 18:37 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-27 7:34 [PATCH v3] dma-buf: Add a capabilities directory Simon Ser
2022-05-30 7:09 ` Christian König
2022-05-30 7:20 ` Greg KH
2022-05-30 8:15 ` Simon Ser
2022-05-30 8:26 ` Greg KH
2022-05-31 12:53 ` Jason Ekstrand
2022-05-31 18:37 ` Greg KH
2022-05-30 7:55 ` Simon Ser
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