uxTaskGetTaskNumber returns 0 due to incorrect TCB handle conversion in ESP-IDF FreeRTOS port (IDFGH-16930)

[tanakamasayuki]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.5-8410210c-v2

Espressif SoC revision.

ESP32-D0WD-V3 (revision v3.1)

Operating System used.

Windows

How did you build your project?

Other (please specify in More Information)

If you are using Windows, please specify command line type.

None

Development Kit.

Freenove ESP32

Power Supply used.

USB

What is the expected behavior?

0 is returned, but I want to get the correct value.

Code

void setup() {
  Serial.begin(115200);
}

void loop() {
  TaskHandle_t h = xTaskGetCurrentTaskHandle();
  printf("name=%s\n", pcTaskGetName(h));

  UBaseType_t taskNumber = uxTaskGetTaskNumber(h);
  printf("taskNumber=%u\n", taskNumber);

  TaskStatus_t info = {};
  vTaskGetInfo(h, &info, pdTRUE, eInvalid);
  printf("info.name=%s\n", info.pcTaskName ? info.pcTaskName : "(null)");
  printf("info.taskNumber=%u\n", info.xTaskNumber);

  delay(1000);
}

Output

name=loopTask
taskNumber=0
info.name=loopTask
info.taskNumber=8

The result of uxTaskGetTaskNumber is strange.

What is the actual behavior?

I want the same number as vTaskGetInfo to be returned.

name=loopTask
taskNumber=8
info.name=loopTask
info.taskNumber=8

Steps to reproduce.

Code

void setup() {
  Serial.begin(115200);
}

void loop() {
  TaskHandle_t h = xTaskGetCurrentTaskHandle();
  printf("name=%s\n", pcTaskGetName(h));

  UBaseType_t taskNumber = uxTaskGetTaskNumber(h);
  printf("taskNumber=%u\n", taskNumber);

  TaskStatus_t info = {};
  vTaskGetInfo(h, &info, pdTRUE, eInvalid);
  printf("info.name=%s\n", info.pcTaskName ? info.pcTaskName : "(null)");
  printf("info.taskNumber=%u\n", info.xTaskNumber);

  delay(1000);
}

Debug Logs.

Diagnostic report archive.

No response

More Information.

xTaskGetCurrentTaskHandle

esp-idf/components/freertos/FreeRTOS-Kernel-SMP/tasks.c

Line 5638 in 4875518

pxTCB = xTask;

vTaskGetInfo

esp-idf/components/freertos/FreeRTOS-Kernel-SMP/tasks.c

Line 6144 in 4875518

pxTCB = prvGetTCBFromHandle( xTask );

[KonstantinKondrashov]

Hi @tanakamasayuki!
Thanks for noticing that. The issue is that uxTaskGetTaskNumber returns uxTaskNumber

esp-idf/components/freertos/FreeRTOS-Kernel/tasks.c

Line 4244 in 4875518

uxReturn = pxTCB->uxTaskNumber;

while vTaskGetInfo returns uxTCBNumber

esp-idf/components/freertos/FreeRTOS-Kernel/tasks.c

Line 4660 in 4875518

pxTaskStatus->xTaskNumber = pxTCB->uxTCBNumber;

The fix for uxTaskGetTaskNumber is:

         if( xTask != NULL )
         {
             pxTCB = xTask;
-            uxReturn = pxTCB->uxTaskNumber;
+            uxReturn = pxTCB->uxTCBNumber;
         }

[tanakamasayuki]

thank you.

esp-idf/components/freertos/FreeRTOS-Kernel-SMP/tasks.c

Line 5666 in 4875518

pxTCB->uxTaskNumber = uxHandle;

pxTCB -> uxTCBNumber = uxHandle ;

Is vTaskSetTaskNumber the same?

[KonstantinKondrashov]

@tanakamasayuki
I am sorry. We double-checked this against upstream FreeRTOS behavior, and the key point is that two different task number fields exist inside the TCB:

uxTCBNumber – assigned automatically by the kernel (incremented each time a task is created). Exposed via vTaskGetInfo() as TaskStatus_t::xTaskNumber. pxTCB->uxTCBNumber has been assigned by the kernel (e.g. 8), so vTaskGetInfo() reports info.xTaskNumber = 8.

uxTaskNumber – user-defined tag, initialized to 0. Can be set by the application using vTaskSetTaskNumber(). Read back using uxTaskGetTaskNumber(). You never call vTaskSetTaskNumber(), so pxTCB->uxTaskNumber remains 0, and uxTaskGetTaskNumber() correctly returns 0.

I agree the API name is a bit confusing (it’s easy to expect it to return the same value as vTaskGetInfo()), but this is inherited directly from upstream FreeRTOS. In ESP-IDF we need to keep the same semantics, so this isn’t an IDF bug as such.

So you have to use vTaskGetInfo() to get TaskStatus_t::xTaskNumber.

[tanakamasayuki]

thank you!