bpf: clarify when bpf_trace_printk discards lines

Browse source

I opened /sys/kernel/tracing/trace once and kept reading from it.
bpf_trace_printk somehow did not seem to work, no entries were appended
to that trace file. It turns out that tracing is disabled when that file
is open. Save the next person some time and document this.

The trace file is described in Documentation/trace/ftrace.rst, however
the implication "tracing is disabled" did not immediate translate to
"bpf_trace_printk silently discards entries".

Signed-off-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

...

This commit is contained in:

Peter Wu 2019-08-21 00:08:59 +01:00 • committed by Alexei Starovoitov

parent 8050a39511

commit 55c33dfbeb

1 changed files with 2 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

2

include/uapi/linux/bpf.h

View file