Messages in this thread | | | From | Axel Rasmussen <> | Date | Fri, 25 Sep 2020 13:57:11 -0700 | Subject | Re: [RFC PATCH 0/1] tracing: support dynamic string field types for synthetic events |
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On Fri, Sep 25, 2020 at 12:48 PM Tom Zanussi <zanussi@kernel.org> wrote: > > Hi Axel, > > On Fri, 2020-09-25 at 12:08 -0700, Axel Rasmussen wrote: > > Hi Steven and Tom, > > > > In this thread: https://lkml.org/lkml/2020/9/17/1015 we discussed how > > to plumb > > dynamic strings into synthetic events. Tom, you proposed adding a new > > dynamic > > string type to synthetic event definition like "char foo[]". > > > > I'm sending this patch because it may be simpler than implementing > > that (I'm > > not too familiar with the tracing infrastructure, apologies if this > > is not > > true), and in my testing it seems sufficient to address my use case. > > I tested > > both setting up a synthetic event as Steven described in the other > > thread, as > > well as doing an analogous thing with a small bpftrace program, and > > both work as > > expected with this patch. > > > > This is because I happen to know there's an upper bound on the length > > of the > > string in question, so I can just define a "char memcg_path[256]" in > > the > > synthetic event, and I can be sure the string won't be truncated. > > > > Let me know what you think. Happy to drop this and wait for Tom's > > suggested > > approach instead. > > Changing check_synth_field() is one of the things that will need to > change for this to work - I'm working on a patch but am kind of in the > middle of it, if you can wait - I expect to be able to post something > Monday... > > Thanks, > > Tom
Absolutely, no problem waiting. I didn't mean to come off as being impatient; mostly since I had already hacked this together a few days ago, I figured it was worth an e-mail in case it could save you some effort. I have no problem dropping it. :) Thanks for working on this!
> > > > > Axel Rasmussen (1): > > tracing: support dynamic string field types for synthetic events > > > > kernel/trace/trace_events_hist.c | 15 ++++++++++++--- > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > -- > > 2.28.0.681.g6f77f65b4e-goog > > >
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