wierd current->uid in module

[project8sem4@fastmail.fm]

hi 
i am new to the kernel. i am working on a simple
 system call interception module that is supposed
 to return the uid of the user who made the call.
 this i do by using current->uid.
 
a fragment of my code:
 
//in kernel module
 asmlinkage long my_mkdir(const char * filename)
 {
         sprintf(buffer,"%s,%i",filename, current->uid);
         //this buffer is later read.
         return original_mkdir( filename);
 }
 
the problem is that the current->uid value always 
turns out to be -1, whether its root or a non-root
 user.
 im using redhat 7.2 (kernel 2.4.7-10)
 can anyone please help me out..
 thanx in advance,
 kt
 

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