From: Lee Jones <lee@xxxxxxxxxx>
A userland application can now operate on the char device with read() in
order to consume a locally held buffer. Memory for the buffer is to be
provisioned and the buffer populated in its subsequently provided
write() counterpart.
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
Reviewed-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
Co-developed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
---
samples/rust/rust_misc_device.rs | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/samples/rust/rust_misc_device.rs b/samples/rust/rust_misc_device.rs
index e7ab77448f754906615b6f89d72b51fa268f6c41..9e4005e337969af764e57a937ae5481d7710cfc9 100644
--- a/samples/rust/rust_misc_device.rs
+++ b/samples/rust/rust_misc_device.rs
@@ -100,8 +100,9 @@
use kernel::{
c_str,
device::Device,
- fs::File,
+ fs::{File, Kiocb},
ioctl::{_IO, _IOC_SIZE, _IOR, _IOW},
+ iov::{IovIterDest, IovIterSource},
miscdevice::{MiscDevice, MiscDeviceOptions, MiscDeviceRegistration},
new_mutex,
prelude::*,
@@ -144,6 +145,7 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
struct Inner {
value: i32,
+ buffer: KVVec<u8>,
}
#[pin_data(PinnedDrop)]
@@ -165,7 +167,10 @@ fn open(_file: &File, misc: &MiscDeviceRegistration<Self>) -> Result<Pin<KBox<Se
KBox::try_pin_init(
try_pin_init! {
RustMiscDevice {
- inner <- new_mutex!( Inner{ value: 0_i32 } ),
+ inner <- new_mutex!(Inner {
+ value: 0_i32,
+ buffer: KVVec::new(),
+ }),
dev: dev,
}
},
@@ -173,6 +178,33 @@ fn open(_file: &File, misc: &MiscDeviceRegistration<Self>) -> Result<Pin<KBox<Se
)
}
+ fn read_iter(mut kiocb: Kiocb<'_, Self::Ptr>, iov: &mut IovIterDest<'_>) -> Result<usize> {
+ let me = kiocb.file();
+ dev_info!(me.dev, "Reading from Rust Misc Device Sample\n");
+
+ let inner = me.inner.lock();
+ // Read the buffer contents, taking the file position into account.
+ let read = iov.simple_read_from_buffer(kiocb.ki_pos_mut(), &inner.buffer)?;
+
+ Ok(read)
+ }
+
+ fn write_iter(mut kiocb: Kiocb<'_, Self::Ptr>, iov: &mut IovIterSource<'_>) -> Result<usize> {
+ let me = kiocb.file();
+ dev_info!(me.dev, "Writing to Rust Misc Device Sample\n");
+
+ let mut inner = me.inner.lock();
+
+ // Replace buffer contents.
+ inner.buffer.clear();
+ let len = iov.copy_from_iter_vec(&mut inner.buffer, GFP_KERNEL)?;
+
+ // Set position to zero so that future `read` calls will see the new contents.
+ *kiocb.ki_pos_mut() = 0;
+
+ Ok(len)
+ }
+
fn ioctl(me: Pin<&RustMiscDevice>, _file: &File, cmd: u32, arg: usize) -> Result<isize> {
dev_info!(me.dev, "IOCTLing Rust Misc Device Sample\n");
--
2.51.0.rc2.233.g662b1ed5c5-goog
