m_get_rcvif and symmetry

[Maxime Villard <max%m00nbsd.net@localhost>]

Hi,
Simply looking at the code, is it normal that m_get_rcvif and m_put_rcvif
are not symmetric [1]? The former always calls pserialize_read_enter, but
the latter may not call pserialize_read_exit.

If it is intentional, please add a comment to clarify.

Thanks,
Maxime

[1] https://nxr.netbsd.org/xref/src/sys/sys/mbuf.h#1014