linux-kernel - Re: Fwd: [PATCH] serial: stm32: fix a recursive locking in stm32_config

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Date:   Thu, 6 Jun 2019 07:42:31 +0000
From:   Erwan LE RAY <erwan.leray@...com>
To:     Borut Seljak <borut.seljak@....net>
CC:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        Jiri Slaby <jslaby@...e.com>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Fwd: [PATCH] serial: stm32: fix a recursive locking in
 stm32_config_rs485

Hi Borut,

Please remove unused "flags" variable declaration.

Erwan.


On 6/4/19 3:55 PM, Erwan LE RAY wrote:
>
>> Hi Borut,
>>
>> Please add the following line in the commit message (before your 
>> sign-off) in a V2 of your patch:
>>
>> Fixes: 1bcda09d291081 ("serial: stm32: add support for RS485 hardware 
>> control mode")
>>
>> I'm OK with the patch itself.
>>
>> Erwan.
>>
>>
>> Subject: [PATCH] serial: stm32: fix a recursive locking in
>>> stm32_config_rs485
>>> Date: Tue,  4 Jun 2019 11:54:51 +0200
>>> From: Borut Seljak <borut.seljak@....net>
>>> CC: Maxime Coquelin <mcoquelin.stm32@...il.com>, Alexandre Torgue
>>> <alexandre.torgue@...com>, Greg Kroah-Hartman
>>> <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org,
>>> borut.seljak@....net, linux-serial@...r.kernel.org, Jiri Slaby
>>> <jslaby@...e.com>, linux-stm32@...md-mailman.stormreply.com,
>>> linux-arm-kernel@...ts.infradead.org
>>>
>>> Remove spin_lock_irqsave in stm32_config_rs485, it cause recursive 
>>> locking.
>>> Already locked in uart_set_rs485_config.
>>>
>>> Signed-off-by: Borut Seljak <borut.seljak@....net>
>>> ---
>>>   drivers/tty/serial/stm32-usart.c | 2 --
>>>   1 file changed, 2 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/stm32-usart.c
>>> b/drivers/tty/serial/stm32-usart.c
>>> index e8d7a7bb4339..da373a465f51 100644
>>> --- a/drivers/tty/serial/stm32-usart.c
>>> +++ b/drivers/tty/serial/stm32-usart.c
>>> @@ -107,7 +107,6 @@ static int stm32_config_rs485(struct uart_port 
>>> *port,
>>>       bool over8;
>>>       unsigned long flags;
- unsigned long flags;
>>>   - spin_lock_irqsave(&port->lock, flags);
>>>       stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
>>>        port->rs485 = *rs485conf;
>>> @@ -147,7 +146,6 @@ static int stm32_config_rs485(struct uart_port 
>>> *port,
>>>       }
>>>        stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
>>> -    spin_unlock_irqrestore(&port->lock, flags);
>>>        return 0;
>>>   }