CC1352R: malloc() hangs the system when running out of heap

user5943842

Part Number: CC1352R

Hi,

I was testing to what would happen if I run out of heap. The below code will quickly hang the system. (In my case after "Hello 3").

printf("Hello 1\n");
malloc(0x4000);
printf("Hello 2\n");
malloc(6500);
printf("Hello 3\n");
malloc(0x8000);
printf("Hello 4\n");

This is not desirable. If there is no heap available, I would assume that it will simply fail and return NULL. However, it is hanging the system.

I have looked at the source code and it is using xdc_runtime_Memory_Alloc(), with an Error_Block. So according to the documentation, the error should be handled, and not lead to a program termination.
I am using CC13x2 SDK 3.20.0.68.

Any insight? I would very much prefer it if the system would just return NULL (no memory allocated) and not hang.

over 5 years ago

0 Severin Suveren over 5 years ago

TI__Mastermind 23730 points

Are you 100 % sure your code hangs after the call to malloc(0x8000)? Have you verified in the debugger that the call does not return?

I'm pretty sure that a failed malloc() will return a NULL pointer instead of hanging the system. So, my theory is that the call to malloc(0x8000) actually succeeds, and the subsequent call to printf() fails. Note that the internals of printf, depending on what you have configured the stdout to route to (serial output?), most likely depends on heap allocations, and since the heap is possibly exhausted it "hangs".

So please verify with a debugger where it crashes.

0 user5943842 over 5 years ago in reply to Severin Suveren

Expert 1550 points

Hi Severin,

Thank you for your response!

I have changed the code to the code shown below, and put breakpoints on each of the malloc() calls.

  malloc(0x4000);
  malloc(0x4000); // Hangs here
  malloc(0x8000); // Never reaches this breakpoint

  printf("Test\n");

The code never reaches the third malloc().

0 Severin Suveren over 5 years ago in reply to user5943842

TI__Mastermind 23730 points

Ok, are you using any specific example to test this on?

0 user5943842 over 5 years ago in reply to Severin Suveren

Expert 1550 points

My code is based on the Simple Peripheral code.

In main.c, I added the code of my previous post after the ICall_createRemoteTasks(), but before creating any other tasks.

0 Severin Suveren over 5 years ago in reply to user5943842

TI__Mastermind 23730 points

And what heap size have you configured?

0 user5943842 over 5 years ago in reply to Severin Suveren

Expert 1550 points

In the .cfg file, this is configured:

var HEAPMGR_CONFIG = 0x82;

So it is autosized and using the HeapTrack heap manager.

0 Severin Suveren over 5 years ago in reply to user5943842

TI__Mastermind 23730 points

So TI-RTOS in the BLE Peripheral example has configured the Error policy to be spin:

Error.policyFxn = Error.policySpin;

This, in addition to that malloc, which is a wrapper to xdc/runtime/Memory, which again is implemented by whatever HEAPMGR_CONFIG is set to, will raise an xdc/runtime/Error whenever the heap manager returns NULL. For an Error.policySpin, this means it will block forever in the spin policy instead of returning a NULL pointer. You can reconfigure the Error policy in the TI-RTOS configuration to be something else than spin, such as Error.policyMin or Error.policyStd for instance.

0 user5943842 over 5 years ago in reply to Severin Suveren

Expert 1550 points

Great and thorough answer, thank you.

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CC1352R: malloc() hangs the system when running out of heap