Linux Serial subsystem development
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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Andy Duan <fugang.duan@nxp.com>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
	"jslaby@suse.com" <jslaby@suse.com>,
	"festevam@gmail.com" <festevam@gmail.com>,
	kernel@pengutronix.de,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Petr Mladek <pmladek@suse.com>
Subject: Re: [PATCH tty/serial 1/1] tty: serial: imx: fix sysrq lockdep issue
Date: Fri, 22 Nov 2019 11:33:59 +0100	[thread overview]
Message-ID: <20191122103359.fud44lh5wl5d3gxe@pengutronix.de> (raw)
In-Reply-To: <1574416632-32321-1-git-send-email-fugang.duan@nxp.com>

Hello,

On Fri, Nov 22, 2019 at 10:00:53AM +0000, Andy Duan wrote:
> From: Fugang Duan <fugang.duan@nxp.com>
> 
> commit dbdda842fe96 ("printk: Add console owner and waiter logic to
> load balance console writes") introduces the lockdep issue for imx
> serial driver in sysrq case:
>      CPU0                    CPU1
>      ----                    ----
> lock(&port_lock_key);
>                              lock(console_owner);
>                              lock(&port_lock_key);
> lock(console_owner);
> 
> It should unlock port_lock_key in handle_sysrq().

I already discussed this problem some time ago but then failed to
complete the topic. You might want to look at the old discussion, see
https://www.spinics.net/lists/kernel/msg3266353.html.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

  reply	other threads:[~2019-11-22 10:34 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-22 10:00 [PATCH tty/serial 1/1] tty: serial: imx: fix sysrq lockdep issue Andy Duan
2019-11-22 10:33 ` Uwe Kleine-König [this message]
2019-11-25  1:23   ` [EXT] " Andy Duan
2019-11-26  9:53     ` Petr Mladek

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