Messages in this thread | | | Subject | Re: [RFC PATCH 0/1] tracing: support dynamic string field types for synthetic events | From | Tom Zanussi <> | Date | Fri, 25 Sep 2020 14:48:48 -0500 |
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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
> > 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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