[DTrace-devel] [PATCH 05/12] Add support for the stack() action

[Eugene Loh]

On 6/9/21 1:21 AM, Eugene Loh wrote:

> On 6/9/21 12:43 AM, Kris Van Hees wrote:
>
>>   Fri, May 28, 2021 at 02:35:09PM -0400,eugene.loh at oracle.com  wrote:
>>> diff --git a/libdtrace/dt_consume.c b/libdtrace/dt_consume.c
>>> @@ -2057,7 +2060,16 @@ dt_consume_one(dtrace_hdl_t *dtp, FILE *fp, char *buf,
>>>   			if (rval != DTRACE_CONSUME_THIS)
>>>   				return dt_set_errno(dtp, EDT_BADRVAL);
>>>   
>>> -			switch (rec->dtrd_action) {
>>> +			if (act == DTRACEACT_STACK) {
>>> +				int depth = rec->dtrd_arg;
>>> +
>>> +				if (dt_print_stack(dtp, fp, NULL, addr, depth,
>>> +				    rec->dtrd_size / depth) < 0)
>>> +					return -1;
>>> +				continue;
>>> +			}
>>> +
>>> +			switch (act) {
>> I truly do not understand why you put the DTRACEACT_STACK case outside the
>> switch, when it could just as easily be part of the switch.
>
> You brought this up with respect to another patch as well, so I 
> figured I'd explain.  The DTv1 code had this sequence of "if 
> (act==foo)" code blocks.  I was simply trying to preserve some of the 
> structure of that code.  Is that a good idea?  Some people will think 
> so some of the time, and others... well.  Anyhow, I posted a v2 of 
> that other patch.  The switch statement ends up impacting other 
> patches and I propagated the change through.
>
> Now, the DTv1 code still had the PRINTF-LIKE actions separately. 
> Sounds like you want everything in one big switch.  Fine by me. I'll 
> do that.  I just figured I'd explain why the code looked the way it did.

One other point.  The code had been structured to look for dt_print_*() 
functions for various actions, and then to look for and handle 
ISPRINTFLIKE actions.  That's why there was code for actions like 
stack(), etc., and then for the printf-like stuff.  I had been trying to 
preserve that structure but, again, seems like you want it squashed 
together so that's what's happening.

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