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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Qian Cai <cai@lca.pw>
Cc: pmladek@suse.com, sergey.senozhatsky.work@gmail.com,
	arnd@arndb.de, peterz@infradead.org, catalin.marinas@arm.com,
	linux-kernel@vger.kernel.org, rostedt@goodmis.org,
	linux-mm@kvack.org, gregkh@linuxfoundation.org,
	longman@redhat.com, dan.j.williams@intel.com, will@kernel.org,
	tglx@linutronix.de, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] char/random: silence a lockdep splat with printk()
Date: Tue, 7 Jan 2020 16:07:24 -0500	[thread overview]
Message-ID: <20200107210724.GN3619@mit.edu> (raw)
In-Reply-To: <1573679785-21068-1-git-send-email-cai@lca.pw>

On Wed, Nov 13, 2019 at 04:16:25PM -0500, Qian Cai wrote:
> From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> 
> Sergey didn't like the locking order,
> 
> uart_port->lock  ->  tty_port->lock
> 
> uart_write (uart_port->lock)
>   __uart_start
>     pl011_start_tx
>       pl011_tx_chars
>         uart_write_wakeup
>           tty_port_tty_wakeup
>             tty_port_default
>               tty_port_tty_get (tty_port->lock)
> 
> but those code is so old, and I have no clue how to de-couple it after
> checking other locks in the splat. There is an onging effort to make all
> printk() as deferred, so until that happens, workaround it for now as a
> short-term fix.

Applied, thanks.

					- Ted

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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Qian Cai <cai@lca.pw>
Cc: arnd@arndb.de, gregkh@linuxfoundation.org,
	sergey.senozhatsky.work@gmail.com, pmladek@suse.com,
	rostedt@goodmis.org, catalin.marinas@arm.com, will@kernel.org,
	dan.j.williams@intel.com, peterz@infradead.org,
	longman@redhat.com, tglx@linutronix.de, linux-mm@kvack.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] char/random: silence a lockdep splat with printk()
Date: Tue, 7 Jan 2020 16:07:24 -0500	[thread overview]
Message-ID: <20200107210724.GN3619@mit.edu> (raw)
In-Reply-To: <1573679785-21068-1-git-send-email-cai@lca.pw>

On Wed, Nov 13, 2019 at 04:16:25PM -0500, Qian Cai wrote:
> From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> 
> Sergey didn't like the locking order,
> 
> uart_port->lock  ->  tty_port->lock
> 
> uart_write (uart_port->lock)
>   __uart_start
>     pl011_start_tx
>       pl011_tx_chars
>         uart_write_wakeup
>           tty_port_tty_wakeup
>             tty_port_default
>               tty_port_tty_get (tty_port->lock)
> 
> but those code is so old, and I have no clue how to de-couple it after
> checking other locks in the splat. There is an onging effort to make all
> printk() as deferred, so until that happens, workaround it for now as a
> short-term fix.

Applied, thanks.

					- Ted


  parent reply	other threads:[~2020-01-07 21:08 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-13 21:16 [PATCH] char/random: silence a lockdep splat with printk() Qian Cai
2019-11-13 21:16 ` Qian Cai
2019-12-03 18:46 ` Qian Cai
2019-12-03 18:46   ` Qian Cai
2019-12-05  1:00   ` Sergey Senozhatsky
2019-12-05  1:00     ` Sergey Senozhatsky
2019-12-17  1:52     ` Qian Cai
2019-12-17  1:52       ` Qian Cai
2020-01-02 15:42       ` Qian Cai
2020-01-02 15:42         ` Qian Cai
2020-01-02 17:07         ` Steven Rostedt
2020-01-02 17:07           ` Steven Rostedt
2020-01-02 17:16           ` Qian Cai
2020-01-02 17:16             ` Qian Cai
2020-01-02 18:00         ` Theodore Y. Ts'o
2020-01-02 18:00           ` Theodore Y. Ts'o
2020-01-07 21:07 ` Theodore Y. Ts'o [this message]
2020-01-07 21:07   ` Theodore Y. Ts'o
2020-03-24 15:13 ` dmesg -w regression in v5.4.22, bisected, was: " Zygo Blaxell
2020-03-24 15:13   ` Zygo Blaxell
2020-03-25  2:35   ` Sergey Senozhatsky
2020-03-25  2:35     ` Sergey Senozhatsky

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