Confusion about possibly unsafe malloc_r?

Dave Nadler
Sun Jun 25 14:28:00 GMT 2017

Thanks Freddie. If I understand your answer correctly, printf's call chain's
use of _GLOBAL_REENT should be OK because this particular memory is
protected by a global lock.

I studied the newlib documentation and looked in syscalls, but did not find
anything explaining how to implement "retargetable locks" as you mention.
I did understand that I must implement env_locks to use set_env/get_env,
and that I did not need to implement the corresponding malloc locks.
I read a half-dozen articles about embedding/porintg newlib and failed
to find this...

Could you point me at documentation (or sources) explaining how
to implement "retargetable locks"?

Thanks for the help!
Best Regards, Dave

On 6/25/2017 2:15 AM, Freddie Chopin wrote:
> On Sat, 2017-06-24 at 18:42 -0400, Dave Nadler wrote:
>> Is this OK? I'm paranoid about thread safety!
> Then it's worth mentioning that newlib and FreeRTOS will _NEVER_ be
> fully thread safe unless you are using a toolchain with retargetable
> locks and your project has support code for these locks.
> printf()-style families partially use global reent structure, this is
> expected. Trace the calls of the mentioned functions in newlib source
> and you'll see that sometimes _GLOBAL_REENT is used, sometimes thread's
> reent.
> Regards,
> FCh

Dave Nadler, USA East Coast voice (978) 263-0097,, Skype

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