tbf: Insert LLC dummy command if no frame is available

If a BSN is going to be created but there is no frame stored in
m_llc, an empty LLC message would be created. This shouldn't happen
currently, but this will be a common case, when delayed TBF release
is implemented.

This commit changes create_new_bsn() to create an LLC dummy
command in that case and to put it into the frame buffer.

Sponsored-by: On-Waves ehf
1 file changed