Fix deadlock in BLECharacteristic::handle_gap_event

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
-      fail-fast: true
+      fail-fast: false
       matrix:
         include:
           - target: riscv32imc-esp-espidf

src/server/ble_characteristic.rs

@@ -323,7 +323,9 @@ impl BLECharacteristic {
     let ctxt = unsafe { &*ctxt };
 
     let mutex = unsafe { voidp_to_ref::<Mutex<Self>>(arg) };
-    let mut characteristic = mutex.lock();
+    let Some(mut characteristic) = mutex.try_lock() else {
+      return sys::BLE_ATT_ERR_UNLIKELY as _;
+    };
 
     if unsafe { sys::ble_uuid_cmp((*ctxt.__bindgen_anon_1.chr).uuid, &characteristic.uuid.u) != 0 }
     {

src/utilities/mutex.rs

@@ -22,6 +22,12 @@ impl RawMutex {
     debug_assert_eq!(r, 0);
   }
 
+  #[inline(always)]
+  #[allow(clippy::missing_safety_doc)]
+  pub unsafe fn try_lock(&self) -> bool {
+    pthread_mutex_trylock(self.0.get()) == 0
+  }
+
   #[inline(always)]
   #[allow(clippy::missing_safety_doc)]
   pub unsafe fn unlock(&self) {
@@ -54,6 +60,11 @@ impl<T> Mutex<T> {
     MutexGuard::new(self)
   }
 
+  #[inline(always)]
+  pub fn try_lock(&self) -> Option<MutexGuard<'_, T>> {
+    MutexGuard::try_new(self)
+  }
+
   #[inline(always)]
   pub(crate) fn into_innter(self) -> T {
     self.1.into_inner()
@@ -79,6 +90,15 @@ impl<'a, T> MutexGuard<'a, T> {
 
     Self(mutex)
   }
+
+  #[inline(always)]
+  fn try_new(mutex: &'a Mutex<T>) -> Option<Self> {
+    if unsafe { mutex.0.try_lock() } {
+      Some(Self(mutex))
+    } else {
+      None
+    }
+  }
 }
 
 impl<'a, T> Drop for MutexGuard<'a, T> {