From: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
To: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>,
Stefan Agner <stefan@agner.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
Wei Yongjun <weiyongjun1@huawei.com>,
Aaron Brice <aaron.brice@datasoft.com>,
Nicolae Rosia <nicolae_rosia@mentor.com>,
linux-serial@vger.kernel.org, Chris Healy <cphealy@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tty: serial: fsl_lpuart: fix del_timer_sync() vs timer routine deadlock
Date: Sat, 3 Dec 2016 11:55:41 +0300 [thread overview]
Message-ID: <68d2fd35-834b-fe74-c9a2-719c7b62a83a@cogentembedded.com> (raw)
In-Reply-To: <9ee78fcd-7aca-e2d3-4df1-fe65a512a0f5@toradex.com>
03.12.2016 10:06, Bhuvanchandra DV пишет:
> On 12/03/2016 02:58 AM, Nikita Yushchenko wrote:
>
>>>> Problem found via lockdep:
>>>>
>>>> - lpuart_set_termios() calls del_timer_sync(&sport->lpuart_timer) while
>>>> holding sport->port.lock
>>>>
>>>> - sport->lpuart_timer routine is lpuart_timer_func() that calls
>>>> lpuart_copy_rx_to_tty() that acquires same lock.
>>>>
>>>> To fix, move Rx DMA stopping out of lock, as it already is in other
>>>> places
>>>> in the same file.
>>>>
>>>> While at it, also make Rx DMA start/stop code to look the same is in
>>>> other places in the same file.
>>> Yeah I saw that too, never really came around to look closer into it.
>>>
>>> Thanks for looking into it.
>>>
>>> You removed the check whether there was an old configuration, I think
>>> the idea of that was that we only resize DMA if it was configured
>>> differently before...
>> Per my code reading, checking for sport->lpuart_dma_rx_use should be
>> enough, this flag will be set only if DMA was previously enabled,
>
> The check is to make sure the reconfiguration of DMA is done only when
> the baudrate is altered.
Then, ok to use
if (old && sport->lpuart_dma_rx_use) {...}
in both places?
next prev parent reply other threads:[~2016-12-03 8:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-02 10:28 [PATCH] tty: serial: fsl_lpuart: fix del_timer_sync() vs timer routine deadlock Nikita Yushchenko
2016-12-02 18:05 ` Stefan Agner
2016-12-02 21:28 ` Nikita Yushchenko
2016-12-03 7:06 ` Bhuvanchandra DV
2016-12-03 8:55 ` Nikita Yushchenko [this message]
2016-12-03 10:06 ` Bhuvanchandra DV
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