lkml.org 
[lkml]   [2013]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/2] tracing: Add $cpu and $current probe-vars
On 11/27, Masami Hiramatsu wrote:
>
> (2013/11/27 2:23), Oleg Nesterov wrote:
> > On 11/26, Masami Hiramatsu wrote:
> >>
> >> (2013/11/26 4:29), Oleg Nesterov wrote:
> >>> +#define PSEUDO_REG_OFFSET 4096 /* arbitrary value > MAX_REG_OFFSET */
> >>> +
> >>> +static unsigned long probe_get_register(struct pt_regs *regs, unsigned long offset)
> >>> +{
> >>> + if (offset < PSEUDO_REG_OFFSET)
> >>> + return regs_get_register(regs, offset);
> >>> +
> >>> + return pseudo_reg_table[offset - PSEUDO_REG_OFFSET].fetch();
> >>> +}
> >>
> >>
> >> Hmm, I don't like this, since fetch_reg is the most frequently
> >> used fetch method, and it actually uses the offset in different
> >> way.
> >
> > Sure, this overloads the usage of FETCH_MTD_reg/offset.
> >
> > And btw, yes, the naming is ugly (I mean pseudo_*). But why this
> > is bad? This is cheap and simple.
>
> I think it's not simple. The code looks short, but not well
> self-described. It is "hidden" in the structure, and double-meaning.

Yes, I agree. And the ugly naming doesn't make it more clear/clean.

I'll try to cleanup this somehow and resend. Perhaps I should start
with 2/2 which generalizes FETCH_MTD_reg and kills FETCH_MTD_retval.
Or at least generalizes FETCH_MTD_retval.

> >> Why don't you make another fetch function for vars?
> >
> > This is what I tried to avoid ;) I do not want to add another
> > FETCH_MTD_. To me, this looks like unnecessary complication and
> > bloat (but see below).
>
> I see, perhaps, it is a time to introduce independent fetch
> method implementation. Current one is not sophisticated
> nor generic

Yes, yes, I agree. But until then I do not want to complicate/blow
this code to implement $current.

Thanks.

Oleg.



\
 
 \ /
  Last update: 2013-11-27 18:21    [W:0.292 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site