Use of xTaskGetApplicationTaskTag within an interrupt handler

casper0 wrote on Monday, March 07, 2016:

I have been using ‘xTaskGetApplicationTaskTag’ to help with debugging tags switches by including it as one of the things to do during a ‘traceTASK_SWITCHED_IN’ event. It’s been “working”, but only that 1) I was using a version of FreeRTOS prior to 8.1.0 for some time, and 2) I did not have ‘configASSERT’ turned on. Both recently changed and now the assertion within ‘vPortEnterCritical’, called from ‘xTaskGetApplicationTaskTag’, fails.

Maybe this is nit picking, since the call’s name does not end with ‘fromISR’, I suppose it now may not be used from within an interrupt call, which the task switch is (‘PendSV_Handler’), anymore. That’s too bad, because it is useful. BUT, when I look at the source for ‘xTaskGetApplicationTaskTag’ it indicates that is ought to be able to be called from within an interrupt (still). Then again, since the ‘vPortEnterCritical’ routine was changed and “became” non-interrupt safe, it will fail the assertion.

What’s the best way for me to continue using this feature? My guess is to use ‘pxCurrentTCB->pxTaskTag’ directly rather than call the function.

And a fix for the ‘xTaskGetApplicationTaskTag’ routine would be to eliminate the comment that indicates it can be used from within a interrupt service routine.

rtel wrote on Tuesday, March 08, 2016:

This comment is relevant to Cortex-M3/4/7 ports only: I think in your case it is still ok to use the function in an interrupt. I would not recomment compiling without configASSERT() though, so perhaps just remove the offending configASSERT() from your build.