Fix a match-spec trace bug that could cause emulator crash

A trace matchspec with 'enable_trace' or 'disable_trace' in body could
cause an emulator crash if a concurrent process altered the trace
setting of the traced function by calling erlang:trace_pattern.

The effect was a deallocation of the binary holding the matchspec
program while it was running. Fixed by increasing reference count of
ms-binary in the cases when 'enable_trace' or 'disable_trace' may
cause a system block that may alter the ongoing trace.

The paradox here is that db_prog_match() is using erts_smp_block_system()
to do 'enable_trace' and 'disable_trace' in a safe (atomic) way. But that
also have the (non-atomic) effect that racing thread might block the
system and change the trace settings with erlang:trace_pattern.

0 files changed, 0 insertions, 0 deletions