Add double modem init protection

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 0.4.3 (2024-06-18)
+
+- Added extra check that prevents initializing the modem multiple times
+- Updated embassy-sync
+- Stopped using `cortex_m::interrupt::free` in favour of `critical_section`
+
 ## 0.4.2 (2024-06-17)
 
 - Fixed a memory ownership issue in `nrf_modem_init`. The `nrf_modem_init_params` pointer given to the init must

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nrf-modem"
-version = "0.4.2"
+version = "0.4.3"
 edition = "2021"
 rust-version = "1.64"
 license = "MIT OR Apache-2.0"
@@ -24,7 +24,7 @@ arrayvec = { version = "0.7", default-features = false }
 at-commands = "0.5.2"
 no-std-net = "0.6.0"
 critical-section = "1.1"
-embassy-sync = "0.3.0"
+embassy-sync = "0.6.0"
 grounded = "0.2.0"
 
 [features]

src/error.rs

@@ -38,6 +38,7 @@ pub enum Error {
     InternalRuntimeMutexLocked,
     /// The given memory layout falls outside of the acceptable range
     BadMemoryLayout,
+    ModemAlreadyInitialized,
 }
 
 pub trait ErrorSource {

src/ffi.rs

@@ -286,7 +286,7 @@ pub extern "C" fn nrfx_ipc_receive_event_disable(event_index: u8) {
 unsafe fn generic_alloc(num_bytes_requested: usize, heap: &crate::WrappedHeap) -> *mut u8 {
     let sizeof_usize = core::mem::size_of::<usize>();
     let mut result = core::ptr::null_mut();
-    cortex_m::interrupt::free(|cs| {
+    critical_section::with(|cs| {
         let num_bytes_allocated = num_bytes_requested + sizeof_usize;
         let layout =
             core::alloc::Layout::from_size_align_unchecked(num_bytes_allocated, sizeof_usize);
@@ -317,7 +317,7 @@ unsafe fn generic_alloc(num_bytes_requested: usize, heap: &crate::WrappedHeap) -
 /// This function is safe to call from an ISR.
 unsafe fn generic_free(ptr: *mut u8, heap: &crate::WrappedHeap) {
     let sizeof_usize = core::mem::size_of::<usize>() as isize;
-    cortex_m::interrupt::free(|cs| {
+    critical_section::with(|cs| {
         // Fetch the size from the previous four bytes
         let real_ptr = ptr.offset(-sizeof_usize);
         let num_bytes_allocated = core::ptr::read_volatile::<usize>(real_ptr as *const usize);

src/gnss.rs

@@ -416,7 +416,8 @@ impl GnssData {
                     )
                     .into_result()?;
 
-                    let data = core::mem::transmute(data.assume_init().nmea_str); // Make data be u8
+                    let data =
+                        core::mem::transmute::<[i8; 83], [u8; 83]>(data.assume_init().nmea_str); // Make data be u8
                     let mut string_data = ArrayString::from_byte_string(&data)?;
                     string_data.truncate(
                         string_data

src/lib.rs

@@ -8,7 +8,7 @@ use core::{
     ops::Range,
     sync::atomic::{AtomicBool, Ordering},
 };
-use cortex_m::interrupt::Mutex;
+use critical_section::Mutex;
 use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
 use linked_list_allocator::Heap;
 
@@ -67,6 +67,7 @@ static LIBRARY_ALLOCATOR: WrappedHeap = Mutex::new(RefCell::new(None));
 static TX_ALLOCATOR: WrappedHeap = Mutex::new(RefCell::new(None));
 
 pub(crate) static MODEM_RUNTIME_STATE: RuntimeState = RuntimeState::new();
+static INITIALIZED: AtomicBool = AtomicBool::new(false);
 
 /// Start the NRF Modem library
 pub async fn init(mode: SystemMode) -> Result<(), Error> {
@@ -78,6 +79,10 @@ pub async fn init_with_custom_layout(
     mode: SystemMode,
     memory_layout: MemoryLayout,
 ) -> Result<(), Error> {
+    if INITIALIZED.fetch_or(true, Ordering::SeqCst) {
+        return Err(Error::ModemAlreadyInitialized);
+    }
+
     const SHARED_MEMORY_RANGE: Range<u32> = 0x2000_0000..0x2002_0000;
 
     if !SHARED_MEMORY_RANGE.contains(&memory_layout.base_address) {
@@ -107,7 +112,7 @@ pub async fn init_with_custom_layout(
         static mut HEAP_MEMORY: [u32; 1024] = [0u32; 1024];
         let heap_start = HEAP_MEMORY.as_ptr() as *mut u8;
         let heap_size = HEAP_MEMORY.len() * core::mem::size_of::<u32>();
-        cortex_m::interrupt::free(|cs| {
+        critical_section::with(|cs| {
             *LIBRARY_ALLOCATOR.borrow(cs).borrow_mut() = Some(Heap::new(heap_start, heap_size))
         });
     }
@@ -148,7 +153,7 @@ pub async fn init_with_custom_layout(
 
     unsafe {
         // Use the same TX memory region as above
-        cortex_m::interrupt::free(|cs| {
+        critical_section::with(|cs| {
             *TX_ALLOCATOR.borrow(cs).borrow_mut() = Some(Heap::new(
                 params.shmem.tx.base as usize as *mut u8,
                 params.shmem.tx.size as usize,