Forward port changes from v0.6 release branch

Merge pico CI fix (#1595) and concurrency issue fix (#1594) from release-0.6.

Author: bettio

.github/workflows/pico-build.yaml

@@ -48,7 +48,7 @@ jobs:
     - name: "Install deps"
       run: |
         sudo apt install -y \
-            cmake gperf ninja-build gcc-arm-none-eabi \
+            cmake doxygen gperf ninja-build gcc-arm-none-eabi \
             libnewlib-arm-none-eabi libstdc++-arm-none-eabi-newlib \
             erlang-base erlang-dev erlang-dialyzer erlang-eunit rebar3
 

src/libAtomVM/scheduler.c

@@ -305,18 +305,16 @@ static void scheduler_make_ready(Context *ctx)
     }
     list_remove(&ctx->processes_list_head);
 #ifndef AVM_NO_SMP
-    bool waiting_scheduler = global->waiting_scheduler;
-    if (!waiting_scheduler) {
+    if (SMP_MUTEX_TRYLOCK(global->schedulers_mutex)) {
         // Start a new scheduler if none are going to take this process.
-        if (SMP_MUTEX_TRYLOCK(global->schedulers_mutex)) {
-            if (global->running_schedulers > 0
-                && global->running_schedulers < global->online_schedulers
-                && !context_get_flags(ctx, Running)) {
-                global->running_schedulers++;
-                smp_scheduler_start(global);
-            }
-            SMP_MUTEX_UNLOCK(global->schedulers_mutex);
+        if (!global->waiting_scheduler
+            && global->running_schedulers > 0
+            && global->running_schedulers < global->online_schedulers
+            && !context_get_flags(ctx, Running)) {
+            global->running_schedulers++;
+            smp_scheduler_start(global);
         }
+        SMP_MUTEX_UNLOCK(global->schedulers_mutex);
     }
 #endif
     // Move to ready queue (from waiting or running)
@@ -326,7 +324,12 @@ static void scheduler_make_ready(Context *ctx)
     list_append(&global->ready_processes, &ctx->processes_list_head);
     SMP_SPINLOCK_UNLOCK(&global->processes_spinlock);
 #ifndef AVM_NO_SMP
-    if (waiting_scheduler) {
+    if (SMP_MUTEX_TRYLOCK(global->schedulers_mutex)) {
+        if (global->waiting_scheduler) {
+            sys_signal(global);
+        }
+        SMP_MUTEX_UNLOCK(global->schedulers_mutex);
+    } else {
         sys_signal(global);
     }
 #elif defined(AVM_TASK_DRIVER_ENABLED)
@@ -410,7 +413,12 @@ void scheduler_set_timeout(Context *ctx, avm_int64_t timeout)
     SMP_SPINLOCK_UNLOCK(&glb->timer_spinlock);
 
 #ifndef AVM_NO_SMP
-    if (glb->waiting_scheduler) {
+    if (SMP_MUTEX_TRYLOCK(glb->schedulers_mutex)) {
+        if (glb->waiting_scheduler) {
+            sys_signal(glb);
+        }
+        SMP_MUTEX_UNLOCK(glb->schedulers_mutex);
+    } else {
         sys_signal(glb);
     }
 #elif defined(AVM_TASK_DRIVER_ENABLED)