Pointer chain paranoia

[Stone, Joshua I]

On Tuesday, November 14, 2006 9:15 AM, Mike Mason wrote:
> I'm looking for opinions from the systemtap community... How paranoid
> should we be when following pointer chains in tapsets and scripts?  I
> think we should use deref() unless we're absolutely sure there's no
> chance of referencing a null or bad pointer, but, of course, that'll
> add a lot of code. I'm not sure how you can ever be absolutely sure,
> particularly for longer chains.  What guidance should we give tapset
> and script writers?      
> 
> Mike

I agree with you.  Safety is always more important than efficiency,
especially in tapsets which may be used by non-guru users.  Any
questionable pointers should be carefully dereferenced, e.g., parameters
passed to functions should be assumed bogus.

When a pointer is known to originate from a kernel source, like from
'current' or as a return value from a kernel function, then we might
relax a bit.


Josh