Messages in this thread | | | From | Andrii Nakryiko <> | Date | Fri, 10 Jul 2020 13:55:10 -0700 | Subject | Re: [PATCH v2 bpf-next 2/2] selftests/bpf: add selftests verifying bpf_trace_printk() behaviour |
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On Fri, Jul 10, 2020 at 7:25 AM Alan Maguire <alan.maguire@oracle.com> wrote: > > Simple selftests that verifies bpf_trace_printk() returns a sensible > value and tracing messages appear. > > Signed-off-by: Alan Maguire <alan.maguire@oracle.com> > ---
see pedantic note below, but I don't think that's an issue in practice
Acked-by: Andrii Nakryiko <andriin@fb.com>
> .../selftests/bpf/prog_tests/trace_printk.c | 74 ++++++++++++++++++++++ > tools/testing/selftests/bpf/progs/trace_printk.c | 21 ++++++ > 2 files changed, 95 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_printk.c > create mode 100644 tools/testing/selftests/bpf/progs/trace_printk.c >
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> + > + /* verify our search string is in the trace buffer */ > + while (read(fd, buf, sizeof(buf)) >= 0 || errno == EAGAIN) {
There is a minor chance that "testing,testing" won't be found, if it so happened that the first part is in the first read buffer, and the second is in the second. I don't think it's ever the case for our CI and for my local testing setup, but could be a cause of some instability if there is something else emitting data to trace_pipe, right?
Maybe line-based reading would be more reliable (unless printk can intermix, not sure about that, in which case there is simply no way to solve this 100% reliably).
> + if (strstr(buf, SEARCHMSG) != NULL) > + found++; > + if (found == bss->trace_printk_ran) > + break; > + if (++iter > 1000) > + break; > + } > + > + if (CHECK(!found, "message from bpf_trace_printk not found", > + "no instance of %s in %s", SEARCHMSG, TRACEBUF)) > + goto cleanup; > + > + printf("ran %d times; last return value %d, with %d instances of msg\n", > + bss->trace_printk_ran, bss->trace_printk_ret, found);
Is this needed or it's some debug leftover?
> +cleanup: > + trace_printk__destroy(skel); > + if (fd != -1) > + close(fd); > +}
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