libtraceevent and threads

Felipe Balbi <balbi@xxxxxxxxxx> · Thu, 15 Dec 2022 19:42:32 +0200

Hi,

I was playing with binding `libtraceevent' to rust today. Generating the
bindings with rust's `bindgen' is very straight forward. When I moved to
porting the existing tests to rust, I found out that running a single
test always worked, while running all tests caused random allocation
failures and (apparent) corruption of the trace_seq buffer.

Upon further investigating the issue, I noticed that asking `cargo' to
run tests in a single thread (essentially one test at a time), always
gave me good results, but as soon as I let `cargo' run 2 threads (or
more) failures would show.

I appears that this is because `libtraceevent' keeps some global state
and that prevents different threads to keep their own "context" of the
library.

I can't say for sure, but it seems that the culprit here is:

	static const char *input_buf;

in line 31 of src/event-parse.c. Would there be a way to hide that
perhaps as part of `struct tep_handle'?

cheers

-- 
balbi