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vTaskDelay no return after blocking operation.

Posted by matita87 on August 23, 2017

Hi all, I using FreeRTOS V9.0.0 on STM32F4 microcontroller for TFTP server. The vTaskDelay never return when it is call after a blocking operation (e.g. after xQueueGenericReceive()) In details, the TFTP listening task is:

void TFTPserverlistening(void pArgs) { // Create a socket // Bind it to the desired port and protocol // Neverending loop while (1) { vTaskDelay(1000); //this works / wait for a connection request (wait a file to upload) - lwip stack / n = recvfrom(sd, &args->request, TFTPMAXMSGLEN, 0, (struct sockaddr )&args->from, (socklent )&fromlen); vTaskDelay(1000); //this dosen't work - NO RETURN }

where the recvfrom is define as lwiprecvfrom. The lwiprecvfrom is part of the lwipstack which use the xQueueGenericReceive in order to wait forever a incoming message. Similar problem can be obtain calling tow time the vTaskDelay with very long dela: vTaskDelay(10000); //this works, yep for 10 seconds it works :) vTaskDelay(1000); //this dosen't work - NO RETURN

Debugging the vTaskDelay and using the trace data log (with keil) I don't have see any problem,

Thanks all. m


vTaskDelay no return after blocking operation.

Posted by rtel on August 23, 2017

Possibilities for vTaskDelay() never returning would be:

1) The task that called vTaskDelay() is being starved out by higher priority tasks that never block.

2) The tick interrupt is not running (when the issue occurs, inspect the xTickCount variable or set a break point in the SysTick_Handler() ISR function or xTaskIncrementTick function to see if the tick count is still incrementing).

3) You have an old fashioned data corruption that has messed up the linked list from which the task is being referenced. Do you have configASSERT() defined? Do you have stack overflow protection turned on?

If everything works fine until recvfrom() is called then have a good look at that function to make sure there is no way it could exit with interrupts disabled, or from inside a critical section.


vTaskDelay no return after blocking operation.

Posted by matita87 on August 24, 2017

Hi Thank you for the reply

1) I don't get your seggestion. Do you think it could be a problem related to priority? The TFTPserverlistening task is created in main function with priority = 6. 2) During vTaskDelay running (never exiting) the system is alive (it is not in halt). The system tick Timer is runinng and the SysTick_Handler(void) routine is correctly executed (xTickCount is incrementing). Even the vApplicationIdleHook is running. 3) Where I can check if the configASSERT() and stack overflow protection are defined? 4) Yes, I am sure that the recvfrom() exit with all interrupts enable. Thanks m


vTaskDelay no return after blocking operation.

Posted by rtel on August 24, 2017

1) I don't get your seggestion. Do you think it could be a problem related to priority? The TFTPserverlistening task is created in main function with priority = 6.

I thought that was a possibility, but as you say that vApplicationIdleHook() is running it seems that is not the case.

2) During vTaskDelay running (never exiting) the system is alive (it is not in halt). The system tick Timer is runinng and the SysTick_Handler(void) routine is correctly executed (xTickCount is incrementing). Even the vApplicationIdleHook is running.

That is very curious then. Are you 100% sure vTaskDelay() is not returning? Have you tried taking a trace recording? (http://www.freertos.org/trace)

3) Where I can check if the configASSERT() and stack overflow protection are defined?

See the following links (and read the book): http://www.freertos.org/a00110.html#configASSERT http://www.freertos.org/Stacks-and-stack-overflow-checking.html http://www.freertos.org/Documentation/RTOS_book.html


vTaskDelay no return after blocking operation.

Posted by matita87 on August 25, 2017

OK thanks Regads


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