Question: are kernel modules with 'dot' legal?

[gstavi]

Due to development constraints I tried to work with 2 drivers for my SRIOV device:
mydev.pf.ko (for PF) and mydev.ko (for VF)

For the PF driver:
Insmod did not report an error.
When using lsmod, I encountered an error of:
libkmod: kmod_module_get_holders: could not open '/sys/module/mydev/holders'

I believe this is due to modname_normalize cutting module basename at first dot rather than last dot.

If this kind of naming is forbidden then insmod should fail as well. It would be nice if Linux build system will warn about it.
If this naming is allowed then lsmod better be fixed.