Re: [PATCH] ring-buffer: Fix polling on trace_pipe

From: Steven Rostedt
Date: Thu Jun 26 2014 - 20:53:35 EST


On Thu, 26 Jun 2014 11:34:46 -0700
Martin Lau <kafai@xxxxxx> wrote:

> Hi Steve,
>
> Can the modified test program reproduce the problem in your test setup?

Ah sorry, got distracted by other work.

OK, I just tried it out, and here's my results:

I ran you code with my current kernel and this is what I got:

# ./ftrace-test-epoll-kafai
<...>-3183 [002] ...1 81.777891: tracing_mark_write:
some data 3183: waitting for more data......
3184: written more data

And it just hung there.


Then I applied your patch, compiled and booted it, and ran the test
again, and I got this:

# ./ftrace-test-epoll-kafai

It just hung there. No forward progress.

I don't think that was the result you intended.

-- Steve


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