[Intel-gfx] [PATCH 2/4] dma-buf: Add ioctls to allow userspace to flush
From: Daniel Vetter
The userspace might need some sort of cache coherency management e.g. when CPU
and GPU domains are being accessed through dma-buf at the same time. To
circumvent this problem there are begin/end coherency markers, that forward
directly to existing dma-buf device drivers vfunc hooks. Userspace can make use
of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The sequence would be
used like following:
- mmap dma-buf fd
- for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
want (with the new data being consumed by the GPU or say scanout device)
- munamp once you don't need the buffer any more
v2 (Tiago): Fix header file type names (u64 -> __u64)
v3 (Tiago): Add documentation. Use enum dma_buf_sync_flags to the begin/end
dma-buf functions. Check for overflows in start/length.
Cc: Sumit Semwal
Signed-off-by: Daniel Vetter
Signed-off-by: Tiago Vignatti
---
Documentation/dma-buf-sharing.txt | 12 ++
drivers/dma-buf/dma-buf.c | 50 +++
include/uapi/linux/dma-buf.h | 43 +
3 files changed, 105 insertions(+)
create mode 100644 include/uapi/linux/dma-buf.h
diff --git a/Documentation/dma-buf-sharing.txt
b/Documentation/dma-buf-sharing.txt
index 480c8de..2d8ee3b 100644
--- a/Documentation/dma-buf-sharing.txt
+++ b/Documentation/dma-buf-sharing.txt
@@ -355,6 +355,18 @@ Being able to mmap an export dma-buf buffer object has 2
main use-cases:
No special interfaces, userspace simply calls mmap on the dma-buf fd.
+ Also, the userspace might need some sort of cache coherency management e.g.
+ when CPU and GPU domains are being accessed through dma-buf at the same
+ time. To circumvent this problem there are begin/end coherency markers, that
+ forward directly to existing dma-buf device drivers vfunc hooks. Userspace
+ can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
+ sequence would be used like following:
+ - mmap dma-buf fd
+ - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
+ to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
+ want (with the new data being consumed by the GPU or say scanout device)
+ - munamp once you don't need the buffer any more
+
2. Supporting existing mmap interfaces in importers
Similar to the motivation for kernel cpu access it is again important that
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 155c146..e628415 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -34,6 +34,8 @@
#include
#include
+#include
+
static inline int is_dma_buf_file(struct file *);
struct dma_buf_list {
@@ -251,11 +253,59 @@ out:
return events;
}
+static long dma_buf_ioctl(struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct dma_buf *dmabuf;
+ struct dma_buf_sync sync;
+ enum dma_data_direction direction;
+
+ dmabuf = file->private_data;
+
+ if (!is_dma_buf_file(file))
+ return -EINVAL;
+
+ switch (cmd) {
+ case DMA_BUF_IOCTL_SYNC:
+ if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
+ return -EFAULT;
+
+ if (sync.flags & DMA_BUF_SYNC_RW)
+ direction = DMA_BIDIRECTIONAL;
+ else if (sync.flags & DMA_BUF_SYNC_READ)
+ direction = DMA_FROM_DEVICE;
+ else if (sync.flags & DMA_BUF_SYNC_WRITE)
+ direction = DMA_TO_DEVICE;
+ else
+ return -EINVAL;
+
+ if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
+ return -EINVAL;
+
+ /* check for overflowing the buffer's size */
+ if (sync.start > dmabuf->size ||
+ sync.length > dmabuf->size - sync.start)
+ return -EINVAL;
+
+ if (sync.flags & DMA_BUF_SYNC_END)
+ dma_buf_end_cpu_access(dmabuf, sync.start,
+ sync.length, direction);
+ else
+ dma_buf_begin_cpu_access(dmabuf, sync.start,
+sync.length, direction);
+
+ return 0;
+ default:
+ return -ENOTTY;
+ }
+}
+
static const struct file_operations dma_buf_fops = {
.release= dma_buf_release,
.mmap = dma_buf_mmap_internal,
.llseek = dma_buf_llseek,
.poll = dma_buf_poll,
+ .unlocked_ioctl = dma_buf_ioctl,
};
/*
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
new file mode 100644
index 000..902c9f6
--- /dev/null
+++ b/include/uapi/linux
Re: [Intel-gfx] [PATCH 2/4] dma-buf: Add ioctls to allow userspace to flush
Hi Tiago,
Thanks for the patch!
On 12 August 2015 at 02:29, Tiago Vignatti wrote:
> From: Daniel Vetter
>
> FIXME: Update kerneldoc for begin/end to make it clear that those are
> for mmap too.
I think if we're going to add this patch upstream, atleast the FIXMEs
should be fixed.
>
> Open: Do we need a special indication that the begin/end is from
> userspace mmap and not from kernel mmap?
>
> There's also the question already about kernel internal users - vmap
> and kmap interfaces are much different ... We might need to add a
> mapping enum to the begin/end dma-buf functions.
Also, this looks like another thing that could be added right now
while we're adding this change.
>
> v2 (Tiago): Fix header file type names (u64 -> __u64)
>
> Signed-off-by: Daniel Vetter
> Signed-off-by: Tiago Vignatti
> ---
> drivers/dma-buf/dma-buf.c| 47
>
> include/uapi/linux/dma-buf.h | 39
> 2 files changed, 86 insertions(+)
> create mode 100644 include/uapi/linux/dma-buf.h
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 155c146..4820d61 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -34,6 +34,8 @@
> #include
> #include
>
> +#include
> +
> static inline int is_dma_buf_file(struct file *);
>
> struct dma_buf_list {
> @@ -251,11 +253,56 @@ out:
> return events;
> }
>
> +static long dma_buf_ioctl(struct file *file,
> + unsigned int cmd, unsigned long arg)
> +{
> + struct dma_buf *dmabuf;
> + struct dma_buf_sync sync;
> + enum dma_data_direction direction;
> +
> + dmabuf = file->private_data;
> +
> + if (!is_dma_buf_file(file))
> + return -EINVAL;
> +
> + switch (cmd) {
> + case DMA_BUF_IOCTL_SYNC:
> + if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
> + return -EFAULT;
> +
> + if (sync.flags & DMA_BUF_SYNC_RW)
> + direction = DMA_BIDIRECTIONAL;
> + else if (sync.flags & DMA_BUF_SYNC_READ)
> + direction = DMA_FROM_DEVICE;
> + else if (sync.flags & DMA_BUF_SYNC_WRITE)
> + direction = DMA_TO_DEVICE;
> + else
> + return -EINVAL;
> +
> + if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
> + return -EINVAL;
> +
> + /* FIXME: Check for overflows in start/length. */
> +
Even this for fixing in this patch itself.
> + if (sync.flags & DMA_BUF_SYNC_END)
> + dma_buf_end_cpu_access(dmabuf, sync.start,
> + sync.length, direction);
> + else
> + dma_buf_begin_cpu_access(dmabuf, sync.start,
> +sync.length, direction);
> +
> + return 0;
> + default:
> + return -ENOTTY;
> + }
> +}
> +
> static const struct file_operations dma_buf_fops = {
> .release= dma_buf_release,
> .mmap = dma_buf_mmap_internal,
> .llseek = dma_buf_llseek,
> .poll = dma_buf_poll,
> + .unlocked_ioctl = dma_buf_ioctl,
> };
>
> /*
> diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
> new file mode 100644
> index 000..e5327df
> --- /dev/null
> +++ b/include/uapi/linux/dma-buf.h
> @@ -0,0 +1,39 @@
> +/*
> + * Framework for buffer objects that can be shared across devices/subsystems.
> + *
> + * Copyright(C) 2015 Intel Ltd
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> by
> + * the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but
> WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> with
> + * this program. If not, see
[Intel-gfx] [PATCH 2/4] dma-buf: Add ioctls to allow userspace to flush
From: Daniel Vetter
FIXME: Update kerneldoc for begin/end to make it clear that those are
for mmap too.
Open: Do we need a special indication that the begin/end is from
userspace mmap and not from kernel mmap?
There's also the question already about kernel internal users - vmap
and kmap interfaces are much different ... We might need to add a
mapping enum to the begin/end dma-buf functions.
v2 (Tiago): Fix header file type names (u64 -> __u64)
Signed-off-by: Daniel Vetter
Signed-off-by: Tiago Vignatti
---
drivers/dma-buf/dma-buf.c| 47
include/uapi/linux/dma-buf.h | 39
2 files changed, 86 insertions(+)
create mode 100644 include/uapi/linux/dma-buf.h
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 155c146..4820d61 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -34,6 +34,8 @@
#include
#include
+#include
+
static inline int is_dma_buf_file(struct file *);
struct dma_buf_list {
@@ -251,11 +253,56 @@ out:
return events;
}
+static long dma_buf_ioctl(struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct dma_buf *dmabuf;
+ struct dma_buf_sync sync;
+ enum dma_data_direction direction;
+
+ dmabuf = file->private_data;
+
+ if (!is_dma_buf_file(file))
+ return -EINVAL;
+
+ switch (cmd) {
+ case DMA_BUF_IOCTL_SYNC:
+ if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
+ return -EFAULT;
+
+ if (sync.flags & DMA_BUF_SYNC_RW)
+ direction = DMA_BIDIRECTIONAL;
+ else if (sync.flags & DMA_BUF_SYNC_READ)
+ direction = DMA_FROM_DEVICE;
+ else if (sync.flags & DMA_BUF_SYNC_WRITE)
+ direction = DMA_TO_DEVICE;
+ else
+ return -EINVAL;
+
+ if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
+ return -EINVAL;
+
+ /* FIXME: Check for overflows in start/length. */
+
+ if (sync.flags & DMA_BUF_SYNC_END)
+ dma_buf_end_cpu_access(dmabuf, sync.start,
+ sync.length, direction);
+ else
+ dma_buf_begin_cpu_access(dmabuf, sync.start,
+sync.length, direction);
+
+ return 0;
+ default:
+ return -ENOTTY;
+ }
+}
+
static const struct file_operations dma_buf_fops = {
.release= dma_buf_release,
.mmap = dma_buf_mmap_internal,
.llseek = dma_buf_llseek,
.poll = dma_buf_poll,
+ .unlocked_ioctl = dma_buf_ioctl,
};
/*
diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h
new file mode 100644
index 000..e5327df
--- /dev/null
+++ b/include/uapi/linux/dma-buf.h
@@ -0,0 +1,39 @@
+/*
+ * Framework for buffer objects that can be shared across devices/subsystems.
+ *
+ * Copyright(C) 2015 Intel Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see
