Operations inside a module

[Matt Young]

Within the open routine of  my module I need to open another device; and the 
write routine needs to write to the other device.

User space system calls seem to be unavailable to module code.
I know about swapping the DS and ES to fake out other modules; then using 
sys_write etc. 

Can my code just include the standard  syscall lib and use them from kernel 
space?

My module code would also like to use user space malloc, is this a problem?

Matt