Prevent idle priority threads from potentially starving the FreeRTOS idle task (#3909)

* FuriThread: Make FuriThreadPriorityIdle equal to the FreeRTOS one, remove FuriThreadPriorityNone
  This magic constant was meaningless,
  FuriThreadPriorityNormal is now assigned by default instead.
* Make furi_thread_list_process private
  Its 'runtime' parameter is to be obtained from FreeRTOS,
  which means apps cannot do it.
* DirectDraw: Remove an useless include and fix memory leak
  Makes this debug app compileable with uFBT out of the box

Co-authored-by: あく <alleteam@gmail.com>

furi/core/thread.c

@@ -1,5 +1,5 @@
 #include "thread.h"
-#include "thread_list.h"
+#include "thread_list_i.h"
 #include "kernel.h"
 #include "memmgr.h"
 #include "memmgr_heap.h"
@@ -65,6 +65,9 @@ struct FuriThread {
 // IMPORTANT: container MUST be the FIRST struct member
 static_assert(offsetof(FuriThread, container) == 0);
 
+// Our idle priority should be equal to the one from FreeRTOS
+static_assert(FuriThreadPriorityIdle == tskIDLE_PRIORITY);
+
 static size_t __furi_thread_stdout_write(FuriThread* thread, const char* data, size_t size);
 static int32_t __furi_thread_stdout_flush(FuriThread* thread);
 
@@ -145,6 +148,8 @@ static void furi_thread_init_common(FuriThread* thread) {
         furi_thread_set_appid(thread, "driver");
     }
 
+    thread->priority = FuriThreadPriorityNormal;
+
     FuriHalRtcHeapTrackMode mode = furi_hal_rtc_get_heap_track_mode();
     if(mode == FuriHalRtcHeapTrackModeAll) {
         thread->heap_trace_enabled = true;
@@ -269,7 +274,7 @@ void furi_thread_set_context(FuriThread* thread, void* context) {
 void furi_thread_set_priority(FuriThread* thread, FuriThreadPriority priority) {
     furi_check(thread);
     furi_check(thread->state == FuriThreadStateStopped);
-    furi_check(priority >= FuriThreadPriorityIdle && priority <= FuriThreadPriorityIsr);
+    furi_check(priority <= FuriThreadPriorityIsr);
     thread->priority = priority;
 }
 
@@ -281,9 +286,7 @@ FuriThreadPriority furi_thread_get_priority(FuriThread* thread) {
 
 void furi_thread_set_current_priority(FuriThreadPriority priority) {
     furi_check(priority <= FuriThreadPriorityIsr);
-
-    UBaseType_t new_priority = priority ? priority : FuriThreadPriorityNormal;
-    vTaskPrioritySet(NULL, new_priority);
+    vTaskPrioritySet(NULL, priority);
 }
 
 FuriThreadPriority furi_thread_get_current_priority(void) {
@@ -345,7 +348,6 @@ void furi_thread_start(FuriThread* thread) {
     furi_thread_set_state(thread, FuriThreadStateStarting);
 
     uint32_t stack_depth = thread->stack_size / sizeof(StackType_t);
-    UBaseType_t priority = thread->priority ? thread->priority : FuriThreadPriorityNormal;
 
     thread->is_active = true;
 
@@ -355,7 +357,7 @@ void furi_thread_start(FuriThread* thread) {
             thread->name,
             stack_depth,
             thread,
-            priority,
+            thread->priority,
             thread->stack_buffer,
             &thread->container) == (TaskHandle_t)thread);
 }

furi/core/thread.h

@@ -30,11 +30,10 @@ typedef enum {
  * @brief Enumeration of possible FuriThread priorities.
  */
 typedef enum {
-    FuriThreadPriorityNone = 0, /**< Uninitialized, choose system default */
-    FuriThreadPriorityIdle = 1, /**< Idle priority */
+    FuriThreadPriorityIdle = 0, /**< Idle priority */
     FuriThreadPriorityLowest = 14, /**< Lowest */
     FuriThreadPriorityLow = 15, /**< Low */
-    FuriThreadPriorityNormal = 16, /**< Normal */
+    FuriThreadPriorityNormal = 16, /**< Normal, system default */
     FuriThreadPriorityHigh = 17, /**< High */
     FuriThreadPriorityHighest = 18, /**< Highest */
     FuriThreadPriorityIsr =

furi/core/thread_list.c

@@ -84,7 +84,7 @@ FuriThreadListItem* furi_thread_list_get_or_insert(FuriThreadList* instance, Fur
 }
 
 void furi_thread_list_process(FuriThreadList* instance, uint32_t runtime, uint32_t tick) {
-    furi_check(instance);
+    furi_assert(instance);
 
     instance->runtime_previous = instance->runtime_current;
     instance->runtime_current = runtime;

furi/core/thread_list.h

@@ -68,14 +68,6 @@ FuriThreadListItem* furi_thread_list_get_at(FuriThreadList* instance, size_t pos
  */
 FuriThreadListItem* furi_thread_list_get_or_insert(FuriThreadList* instance, FuriThread* thread);
 
-/** Process items in the FuriThreadList instance
- *
- * @param      instance  The instance
- * @param[in]  runtime   The runtime of the system since start
- * @param[in]  tick      The tick when processing happened
- */
-void furi_thread_list_process(FuriThreadList* instance, uint32_t runtime, uint32_t tick);
-
 /** Get percent of time spent in ISR
  *
  * @param      instance  The instance

furi/core/thread_list_i.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "thread_list.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Process items in the FuriThreadList instance
+ *
+ * @param      instance  The instance
+ * @param[in]  runtime   The runtime of the system since start
+ * @param[in]  tick      The tick when processing happened
+ */
+void furi_thread_list_process(FuriThreadList* instance, uint32_t runtime, uint32_t tick);
+
+#ifdef __cplusplus
+}
+#endif