Running NIF code in driver handlers

Max Lapshin max.lapshin@REDACTED
Tue Sep 15 16:53:18 CEST 2020

I've got ab interesting bug.

I have a driver (it is more convenient than NIF to handle sockets
because the driver has state).

I tried to call enif_make_maps from  port_call callback and got into
following backtrace:

erts_maps_put is calling erts_hashmap_insert
then it goes into macro ERTS_VERIFY_UNUSED_TEMP_ALLOC(p);
then goes to erts_proc_sched_data

Problem is following:  I call   env  = enif_alloc_env();
but I'm running on a scheduler thread, because it is driver port_call callback.
I do not have any working process, so c_p->scheduler_data  is zero,
thus this code assumes that I'm on a dirty scheduler thread.

So it seems that it is illegal to call enif_alloc_env in a driver callback and
maybe even illegal to do it in a NIF callback because we already have env?

Should I create a better test example?  Is it a designed behaviour or
something that
can be fixed?

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