Race condition with parallel recursive make

[Christian Rishøj Jensen]

I have a project with several sub-directories, each having some targets which 
share a common dependency. The sub-directories are handled by spawning 
sub-makes (using the special $(MAKE) variable).

Now, when running make with e.g. -j4 I see that several of the sub-makes are 
attempting to build the common dependency at the same time. This is obviously 
not desirable. 

I was under the impression that the jobserver would prevent such situations, by 
keeping track of what each sub-make is doing. I might be mistaken. Can someone 
cast some light on this?

Is there a method for avoiding this sort of race condition?

Thanks.

/ Christian