Re: Question on checking the stack

[Bryce <philip.copeland@oracle.com>]

Frank Ch. Eigler wrote:

>Bryce <philip.copeland@oracle.com> writes:
>
>  
>
>>Setting up a probe for a function is great and all but is there a way
>>to test how we entered the routine?
>>[...]
>>    
>>
>
>Just about all the essentials are in there somewhere, just
>not in a convenient-to-use form.
>
>  
>
>>probe kernel.function("generic_make_request") {
>>    if (stack(1) == "submit_bio" ) { // where stack(1) was the last
>>routine  and stack(2) was 2nd last etc
>>         do_test/display
>>    }
>>}
>>    
>>
>
>The tapset/context.stp file would need two new functions such as these:
>
>  caller:string(n:long) - returns the nth substring as if from backtrace()
>  addr2symbol:string(n:long) - address-to-symbol lookup, which is exactly
>                               one stage of print_stack()
>
>- FChE
>  
>

*nod* Just Sebastiaens hack has the unfortunate problem of needing to 
know in advance what all the exit addresses from a routine and combing 
the stack looking for a string match is probably rather slow if it 
happens often enough.

Cheers

Phil
=--=