Implement sys_free_tx_buffer

src/drivers/net/mod.rs

@@ -26,8 +26,12 @@ pub trait NetworkInterface {
 	/// Returns the current MTU of the device.
 	fn get_mtu(&self) -> u16;
 	/// Get buffer to create a TX packet
+	///
+	/// This returns ownership of the TX buffer.
 	fn get_tx_buffer(&mut self, len: usize) -> Result<(*mut u8, usize), ()>;
-	/// Send TC packets
+	/// Frees the TX buffer (takes ownership)
+	fn free_tx_buffer(&self, token: usize);
+	/// Send TC packets (takes TX buffer ownership)
 	fn send_tx_buffer(&mut self, tkn_handle: usize, len: usize) -> Result<(), ()>;
 	/// Check if a packet is available
 	fn has_packet(&self) -> bool;

src/drivers/net/rtl8139.rs

@@ -241,6 +241,10 @@ impl NetworkInterface for RTL8139Driver {
 		}
 	}
 
+	fn free_tx_buffer(&self, _token: usize) {
+		// get_tx_buffer did not allocate
+	}
+
 	fn send_tx_buffer(&mut self, id: usize, len: usize) -> Result<(), ()> {
 		// send the packet
 		unsafe {

src/drivers/net/virtio_net.rs

@@ -543,6 +543,10 @@ impl NetworkInterface for VirtioNetDriver {
 		}
 	}
 
+	fn free_tx_buffer(&self, token: usize) {
+		unsafe { drop(Box::from_raw(token as *mut BufferToken)) }
+	}
+
 	fn send_tx_buffer(&mut self, tkn_handle: usize, _len: usize) -> Result<(), ()> {
 		// This does not result in a new assignment, or in a drop of the BufferToken, which
 		// would be dangerous, as the memory is freed then.

src/syscalls/interfaces/mod.rs

@@ -154,6 +154,19 @@ pub trait SyscallInterface: Send + Sync {
 		Err(())
 	}
 
+	fn free_tx_buffer(&self, handle: usize) -> Result<(), ()> {
+		#[cfg(all(feature = "pci", not(target_arch = "aarch64")))]
+		match arch::kernel::pci::get_network_driver() {
+			Some(driver) => {
+				driver.lock().free_tx_buffer(handle);
+				Ok(())
+			}
+			_ => Err(()),
+		}
+		#[cfg(not(all(feature = "pci", not(target_arch = "aarch64"))))]
+		Err(())
+	}
+
 	fn send_tx_buffer(&self, handle: usize, len: usize) -> Result<(), ()> {
 		#[cfg(all(feature = "pci", not(target_arch = "aarch64")))]
 		match arch::kernel::pci::get_network_driver() {

src/syscalls/mod.rs

@@ -114,6 +114,16 @@ extern "C" fn __sys_get_tx_buffer(len: usize, ret: &mut Result<(*mut u8, usize),
 	*ret = unsafe { SYS.get_tx_buffer(len) };
 }
 
+#[allow(improper_ctypes_definitions)]
+extern "C" fn __sys_free_tx_buffer(handle: usize) -> Result<(), ()> {
+	unsafe { SYS.free_tx_buffer(handle) }
+}
+
+#[no_mangle]
+pub fn sys_free_tx_buffer(handle: usize) -> Result<(), ()> {
+	kernel_function!(__sys_free_tx_buffer(handle))
+}
+
 #[no_mangle]
 pub fn sys_get_tx_buffer(len: usize) -> Result<(*mut u8, usize), ()> {
 	let mut ret = Err(());