add trace-mode-selective flag

- update rtos-trace selective to depend on trace-mode-selective
- gate trace_excluded field behind trace-mode-selective instead of trace
- reduce memory overhead when selective tracing is not needed

Author: kat-perez

embassy-executor/Cargo.toml

@@ -95,10 +95,12 @@ executor-thread = []
 executor-interrupt = []
 ## Enable tracing support (adds some overhead)
 trace = []
+## Enable selective tracing support
+trace-mode-selective = ["trace"]
 ## Enable support for rtos-trace framework (traces all tasks by default)
 rtos-trace = ["dep:rtos-trace", "trace", "dep:embassy-time-driver"]
 ## Only trace tasks that are explicitly marked for tracing (selective mode)
-rtos-trace-selective = ["rtos-trace"]
+rtos-trace-selective = ["rtos-trace", "trace-mode-selective"]
 
 #! ### Timer Item Payload Size
 #! Sets the size of the payload for timer items, allowing integrated timer implementors to store

embassy-executor/src/raw/mod.rs

@@ -93,7 +93,7 @@ pub(crate) struct TaskHeader {
     pub(crate) name: Option<&'static str>,
     #[cfg(feature = "trace")]
     pub(crate) id: u32,
-    #[cfg(feature = "trace")]
+    #[cfg(feature = "trace-mode-selective")]
     pub(crate) trace_excluded: bool,
     #[cfg(feature = "trace")]
     all_tasks_next: AtomicPtr<TaskHeader>,
@@ -196,7 +196,7 @@ impl<F: Future + 'static> TaskStorage<F> {
                 name: None,
                 #[cfg(feature = "trace")]
                 id: 0,
-                #[cfg(feature = "trace")]
+                #[cfg(feature = "trace-mode-selective")]
                 trace_excluded: cfg!(feature = "rtos-trace-selective"),
                 #[cfg(feature = "trace")]
                 all_tasks_next: AtomicPtr::new(core::ptr::null_mut()),

embassy-executor/src/raw/trace.rs

@@ -213,14 +213,22 @@ impl TaskRefTrace for TaskRef {
     }
 
     fn is_trace_excluded(&self) -> bool {
-        self.header().trace_excluded
+        #[cfg(feature = "trace-mode-selective")]
+        {
+            self.header().trace_excluded
+        }
+        #[cfg(not(feature = "trace-mode-selective"))]
+        false
     }
 
     fn set_trace_excluded(&self, excluded: bool) {
+        #[cfg(feature = "trace-mode-selective")]
         unsafe {
             let header_ptr = self.ptr.as_ptr() as *mut TaskHeader;
             (*header_ptr).trace_excluded = excluded;
         }
+        #[cfg(not(feature = "trace-mode-selective"))]
+        let _ = excluded;
     }
 }