Messages in this thread | | | Subject | Re: [PATCH 1/5] ftrace: Synchronize variable setting with breakpoints | From | Peter Zijlstra <> | Date | Thu, 31 May 2012 20:03:33 +0200 |
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On Thu, 2012-05-31 at 13:53 -0400, Steven Rostedt wrote: > On Thu, 2012-05-31 at 19:40 +0200, Peter Zijlstra wrote: > > On Thu, 2012-05-31 at 10:08 -0400, Steven Rostedt wrote: > > > > Also, why does this stuff live in ftrace? I always thought you were > > > > going to replace text_poke() so everybody that uses cross-modifying code > > > > could profit? > > > > > > I discussed this with Masami at Collaboration Summit. The two are > > > similar but also very different. But we want to start merging the two > > > together where it makes sense. > > > > Argh,. I so disagree. You're doing it backwards. > > > > First you merge whatever is there, regardless of who came first. > > The comment about coming first was more about 're-inventing' then about > merging. You can't reinvent something that didn't exist. > > That said, I didn't even think about text poke while doing this.
Well, the fail is before that, how could we grow two pieces of code doing similar things in the first place?
> I was > just simply thinking about removing stop_machine from ftrace, that > required this. It was only a after thought that text_poke() could do the > same. And this came up at Collab, where I thought, oh yeah! we can > incorporate this with text poke.
But but but but.. the thing far back when Mathieu proposed the int3 scheme it was text_poke().. how.. did you not think of it this time!?
> > > Then, when everybody doing text modification is using the same > > interface, do a second implementation using a Kconfig knob. If the scary > > new one breaks, no sweat, flip the config. If its proven stable, kill > > off the old one. > > What do you suggest then? To revert the code and rewrite it so that > text_poke() does a similar thing?
Too late for that now I guess.. I just wonder why you all thought it was a good idea to have two pieces of code doing cross-modifying-code. I always assumed ftrace used text_poke().
I hardly ever use dyn-ftrace but I do use some text_poke() through jump_labels.
I would still like to end up with one code base doing CMC with two implementations depending on a Kconfig knob.
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