Messages in this thread | | | Date | Fri, 11 Jun 2021 10:50:11 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] kprobes: Print an error if probe is rejected |
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On Thu, 10 Jun 2021 13:33:46 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 10 Jun 2021 19:16:43 +0900 > Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > Hmm, Nack for this way, but I understand that is a problem. > > If you got the error in perf probe, which uses ftrace dynamic-event interface. > > In that case, the errors should not be output in the dmesg, but are reported > > via error_log in tracefs. > > And kprobes itself should return different error code to the caller, instead > > of printing error in dmesg. See below. > > We should update perf to use libtracefs that also has an interface to > read the error_log file.
Hmm, it seems that libtracefs has no parser for the error_log file.
What we need is to parse error_log and find appropriate entry of the error log. Thus, the interface will be;
int tracefs_add_dynamic_event(const char *command, char **error_log);
And the usage will be;
ret = tracefs_add_dynamic_event(command, &error_buf); if (ret < 0) { pr_error("Failed to add dynamic event: %d\n", ret); pr_error("Error log:\n%s\n", error_buf); free(error_buf); return ret; } ... This is because error_log file keeps some previous error logs and you need to find appropriate one from the actual command.
Maybe a part of perf probe (util/probe-file.c) should be shared with libtracefs and finally it should moved on the libtracefs.
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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