linux-kernel - Re: PNP0501 serial driver takes almost 2 seconds to suspend/resume (printk issue)

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Date:   Wed, 13 Jul 2022 07:24:43 -0700
From:   Todd Brandt <todd.e.brandt@...ux.intel.com>
To:     John Ogness <john.ogness@...utronix.de>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: PNP0501 serial driver takes almost 2 seconds to suspend/resume
 (printk issue)

On Wed, 2022-07-13 at 11:57 +0206, John Ogness wrote:
> On 2022-07-11, Sergey Senozhatsky <senozhatsky@...omium.org> wrote:
> > > It seems that __pr_flush() does not check whether all consoles
> > > are
> > > suspended. In this case the progress is not possible and it has
> > > to
> > > wait the entire timeout.
> > 
> > But isn't console_suspended set after pr_flush() call?
> 
> There should not be any printing after the suspend_console() message.
> If
> Todd's report is coming from 5.19-rc1, then it is likely a kthread
> issue, where the kthread is not respecting @console_suspended. (This
> would still need to be fixed for the kthreads, but would not be
> relevant
> for 5.19.)
> 
> John

It appears to still be there in rc5 (our lab system is usually 6 days
behind, so rc6 hasn't been run yet). I'm building a new rc6 kernel with
CONFIG_PRINTK_CALLER today and will run it on all affected machines,
I'll send out the data this afternoon Oregon Time. I'll include
timelines for all affected machines to give you a better sampling.