[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 30 Oct 2014 21:16:36 -0400 (EDT)
From: Vince Weaver <vince@...ter.net>
To: Peter Zijlstra <peterz@...radead.org>
cc: Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Jiri Olsa <jolsa@...hat.com>,
Matt Fleming <matt@...sole-pimps.org>,
Andy Lutomirski <luto@...capital.net>,
Stephane Eranian <eranian@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: Re: [RFD] perf syscall error handling
On Thu, 30 Oct 2014, Peter Zijlstra wrote:
> So would something simple, like an offset into the struct
> perf_event_attr pointing at the current field we're trying to process
> make sense? Maybe with negative offsets to indicate the syscall
> arguments?
>
> That would narrow down the 'WTF is wrong noaw' a lot I think. But then,
> I've not actually done a lot of userspace the last few years, so maybe
> I'm just dreaming things.
well, as someone who spends a lot of time in userspace trying to help
people who report probems like 'perf_event_open() returns EINVAL, what's
wrong' I can say pretty much anything will be an improvement.
What would really help is if we could somehow return the
filename/line-number of whatever source code file that's setting errno.
Even if perf_event_open() told me that hey, we're getting EOPNOTSUPP due
to the precise_ip parameter (something that happened just yesterday) it's
still a lot of grepping and poking around source files to find out what's
going on. It would be much better if it just told me the issue was at
kernel/events/core.c line 995 or so, but I'm not sure how you could pass
that back to the user, and one could argue it wouldn't help much the
average user without a kernel tree lying around.
Vince
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists