[ltt-dev] [UST PATCH] Fix the once in a while freeze of the tests

[Mathieu Desnoyers]

* Yannick Brosseau (yannick.brosseau at gmail.com) wrote:
> Sometimes, the thread in the read function would lock the pipe so the
> setlinebuf would freeze on it. Set the linebuf before we create the
> thread to fix this deadlock

Can you update the description to show which locks are involved in this
deadlock scenario ? E.g.

- CPU A               - CPU B

function              function
lock A (taken)        lock B (taken)
lock B (waiting)
                      lock A (waiting)  <-- deadlock

Or show it with the lock chain dependency analysis. But it's important
to have this information along with this kind of fix.

Thanks,

Mathieu
> 
> Signed-off-by: Yannick Brosseau <yannick.brosseau at gmail.com>
> ---
>  tests/tap.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/tests/tap.c b/tests/tap.c
> index a54fd17..4bb695e 100644
> --- a/tests/tap.c
> +++ b/tests/tap.c
> @@ -58,6 +58,9 @@ static void tap_comment_stdout(void)
>  		goto close_pipe;
>  	}
>  
> +	/* Set it before we create the reading thread */
> +	setlinebuf(pipe_r_file);
> +
>  	stdout_fileno = fileno(stdout);
>  	if (stdout_fileno < 0) {
>  		perror("# Couldn't get fileno for stdout!?");
> @@ -112,7 +115,7 @@ static void tap_comment_stdout(void)
>  
>  	setlinebuf(stdout);
>  	setlinebuf(stderr);
> -	setlinebuf(pipe_r_file);
> +
>  
>  	return;
>  
> -- 
> 1.7.2.3
> 
> 
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com