All of lore.kernel.org
 help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Greg KH <greg@kroah.com>
Cc: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	linux-serial@vger.kernel.org, Wolfram Sang <wsa@the-dreams.de>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Subject: Re: [PATCH] serial: sh-sci: prevent lockup on full TTY buffers
Date: Mon, 19 Feb 2018 09:20:10 +0100	[thread overview]
Message-ID: <CAMuHMdVT1zL3UTbRZjErvxGC21HVV-zAmsqBZgvZA5a5Y=S7bw@mail.gmail.com> (raw)
In-Reply-To: <20180216184406.GA9286@kroah.com>

Hi Greg,

On Fri, Feb 16, 2018 at 7:44 PM, Greg KH <greg@kroah.com> wrote:
> On Thu, Feb 15, 2018 at 01:02:27PM +0100, Ulrich Hecht wrote:
>> When the TTY buffers fill up to the configured maximum, a system lockup
>> occurs:
>>
>> [  598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks:
>> [  598.825796]  0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1
>> [  598.832577]  (detected by 3, t=62517 jiffies, g=296, c=295, q=126)
>> [  598.838755] Task dump for CPU 0:
>> [  598.841977] swapper/0       R  running task        0     0      0 0x00000022
>> [  598.849023] Call trace:
>> [  598.851476]  __switch_to+0x98/0xb0
>> [  598.854870]            (null)
>>
>> This can be prevented by doing a dummy read of the RX data register.
>>
>> This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0;
>> reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms
>> as well.
>>
>> Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
>> Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
>
> Should this go to older kernel versions as well?
> If so, how far back?

This code path dates back to full-history-linux commit 2898a0e08c6ffb63
("[PATCH] SH Merge") in 2.6.2, back in 2004.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2018-02-19  8:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-15 12:02 [PATCH] serial: sh-sci: prevent lockup on full TTY buffers Ulrich Hecht
2018-02-15 13:12 ` Wolfram Sang
2018-02-16 14:27   ` Ulrich Hecht
2018-02-19  8:16     ` Geert Uytterhoeven
2018-02-16 18:44 ` Greg KH
2018-02-19  8:20   ` Geert Uytterhoeven [this message]
2018-02-19  8:21 ` Yoshihiro Shimoda

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAMuHMdVT1zL3UTbRZjErvxGC21HVV-zAmsqBZgvZA5a5Y=S7bw@mail.gmail.com' \
    --to=geert@linux-m68k.org \
    --cc=greg@kroah.com \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=linux-serial@vger.kernel.org \
    --cc=ulrich.hecht+renesas@gmail.com \
    --cc=wsa@the-dreams.de \
    --cc=yoshihiro.shimoda.uh@renesas.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.