Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 7 Jan 2020 16:07:24 -0500
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()
Message-ID: <20200107210724.GN3619@mit.edu>
References: <1573679785-21068-1-git-send-email-cai@lca.pw>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1573679785-21068-1-git-send-email-cai@lca.pw>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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