lib: rust_support: remove incorrect try_lock function and uses

It appears that try_lock is only used to support formatting of the
Trusty mutex wrapper so we remove formatting for now since it is
faster than fixing the implementation and adding tests for it.

Test: build.py generic-x86_64-test
Bug: 298705967
Change-Id: Ia0f1ab7269080f8ae9543875942067ff3c375950

2 files changed, 0 insertions, 32 deletions

diff --git a/lib/rust_support/rules.mk b/lib/rust_support/rules.mk
index 3840b782..fdf652ee 100644
--- a/lib/rust_support/rules.mk
+++ b/lib/rust_support/rules.mk
@@ -36,7 +36,6 @@ MODULE_DEPS := \
 
 MODULE_BINDGEN_ALLOW_FUNCTIONS := \
 	_panic \
-	extern_is_mutex_held \
 	mutex_acquire_timeout \
 	mutex_destroy \
 	mutex_init \
diff --git a/lib/rust_support/sync.rs b/lib/rust_support/sync.rs
index eac9eaa2..0bfc3fe1 100644
--- a/lib/rust_support/sync.rs
+++ b/lib/rust_support/sync.rs
@@ -22,9 +22,6 @@
  */
 
 use core::cell::UnsafeCell;
-use core::fmt;
-use core::fmt::Debug;
-use core::fmt::Formatter;
 use core::mem;
 use core::ops::Deref;
 use core::ops::DerefMut;
@@ -32,7 +29,6 @@ use core::ops::DerefMut;
 use alloc::boxed::Box;
 
 use crate::err::NO_ERROR;
-use crate::sys::extern_is_mutex_held;
 use crate::sys::mutex_acquire_timeout;
 use crate::sys::mutex_destroy;
 use crate::sys::mutex_init;
@@ -146,16 +142,6 @@ impl<T: ?Sized> Mutex<T> {
         assert_eq!(status, NO_ERROR);
         MutexGuard { lock: &self }
     }
-
-    pub fn try_lock(&self) -> Option<MutexGuard<'_, T>> {
-        // SAFETY: `extern_is_mutex_held` is thread safe and it was `mutex_init`ialized.
-        let locked = unsafe { extern_is_mutex_held(self.mutex.get_raw()) };
-        if locked {
-            None
-        } else {
-            Some(self.lock())
-        }
-    }
 }
 
 impl<T: ?Sized> Drop for MutexGuard<'_, T> {
@@ -197,20 +183,3 @@ impl<T> From<T> for Mutex<T> {
         Self::new(value)
     }
 }
-
-/// Copied from [`std::sync::Mutex`],
-/// with minor changes as [`Mutex`] has no poisoning.
-impl<T: ?Sized + Debug> Debug for Mutex<T> {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        let mut d = f.debug_struct("Mutex");
-        match self.try_lock() {
-            Some(guard) => {
-                d.field("data", &&*guard);
-            }
-            None => {
-                d.field("data", &format_args!("<locked>"));
-            }
-        }
-        d.finish_non_exhaustive()
-    }
-}