linux-kernel - Re: [for-linus][PATCH 0/3] ktest.pl: Fix ssh hanging and reseting of console

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Message-Id: <20230120181059.98a4094eb4267b77f156bc39@kernel.org>
Date:   Fri, 20 Jan 2023 18:10:59 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org,
        "John Warthog9 Hawley" <warthog9@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [for-linus][PATCH 0/3] ktest.pl: Fix ssh hanging and reseting
 of console

On Wed, 18 Jan 2023 16:54:35 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> I've noticed that my ssh sessions would hang during test runs, which
> is really frustrating when you kick off a 13 hour test before going to
> bed, and the second test (1 hour into it) hangs, and you need to kick
> it off again in the morning (wasting all that time over night).
> 
> I finally figured out the cause. There is a disconnect between
> the run_command that executes the test, and the "wait_for_input" that
> monitors the test. The wait_for_input has a default of 2 minute timeout
> if it doesn't see any output it returns. The run_command takes the
> empty string from wait_for_input as the test is finished, and then
> stops monitoring it, and calls waitpid() waiting for the test to
> exit.
> 
> The problem is that if the test has a lot of output, it will continue
> writing into the pipe that was suppose to go to the monitor, which has
> now exited the loop. When the pipe fills up, it will not finish.
> When the test is over, it just hangs waiting for the pipe to flush
> (which never happens).
> 
> To fix this, change the run_command to by default have an infinite
> run (which can be overridden by the new RUN_TIMEOUT option), and
> make the wait_for_input also wait indefinitely in this case. It now
> Now the tests will have its content continuously read and will exit
> normally.
> 
> While debugging this, I also found out why you can lose stdout on
> the terminal sometimes. Especially if you hit Ctrl^C while the monitor
> is running. It was due to missing "end_monitor" which gives back the
> tty to the terminal. The first two patches fix that.
> 
> 

Thanks for updating. I ran the test and confirmed that the terminal
setting is recovered :)

Tested-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

BTW, I found another issue that if I didn't set up sendmail,
it doesn't recover stty. Let me send a fix.

> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-ktest.git
> devel

Also, this devel branch seems not pushed yet.

Thank you,

> 
> Head SHA1: aa9aba9382884554fe6a303744884866d137422d
> 
> 
> Steven Rostedt (3):
>       ktest.pl: Fix missing "end_monitor" when machine check fails
>       ktest.pl: Give back console on Ctrt^C on monitor
>       ktest.pl: Add RUN_TIMEOUT option with default unlimited
> 
> ----
>  tools/testing/ktest/ktest.pl    | 26 +++++++++++++++++++++-----
>  tools/testing/ktest/sample.conf |  5 +++++
>  2 files changed, 26 insertions(+), 5 deletions(-)


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>