From: "S, Shirish" <sshankar@amd.com>
To: Tony Lindgren <tony@atomide.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>,
Andy Shevchenko <andy.shevchenko@gmail.com>,
Raul Rangel <rrangel@google.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
kurt@linutronix.de, "S, Shirish" <Shirish.S@amd.com>,
Peter Zijlstra <peterz@infradead.org>,
John Ogness <john.ogness@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: UART/TTY console deadlock
Date: Wed, 1 Jul 2020 12:14:35 +0530 [thread overview]
Message-ID: <3b665cbd-7afb-b72d-22c0-7dc1543ac42e@amd.com> (raw)
In-Reply-To: <20200630180255.GD37466@atomide.com>
On 6/30/2020 11:32 PM, Tony Lindgren wrote:
> * Sergey Senozhatsky <sergey.senozhatsky@gmail.com> [200630 13:06]:
>> On (20/06/30 14:22), Petr Mladek wrote:
> ...
>
>>>>>> @@ -2284,8 +2289,6 @@ int serial8250_do_startup(struct uart_port *port)
>>>>>> * allow register changes to become visible.
>>>>>> */
>>>>>> spin_lock_irqsave(&port->lock, flags);
>>>>>> - if (up->port.irqflags & IRQF_SHARED)
>>>>>> - disable_irq_nosync(port->irq);
>>>>>>
>>>>>> wait_for_xmitr(up, UART_LSR_THRE);
>>>>>> serial_port_out_sync(port, UART_IER, UART_IER_THRI);
>>>>>> @@ -2297,9 +2300,9 @@ int serial8250_do_startup(struct uart_port *port)
>>>>>> iir = serial_port_in(port, UART_IIR);
>>>>>> serial_port_out(port, UART_IER, 0);
>>>>>>
>>>>>> - if (port->irqflags & IRQF_SHARED)
>>>>>> - enable_irq(port->irq);
>>>>>> spin_unlock_irqrestore(&port->lock, flags);
>>>>>> + if (irq_shared)
>>>>>> + enable_irq(port->irq);
>>>>>>
>>>>>> /*
>>>>>> * If the interrupt is not reasserted, or we otherwise
>>>>> I think that it might be safe but I am not 100% sure, sigh.
>>>> Yeah, I'm not 100%, but I'd give it a try.
>>> I do not feel brave enough to ack it today. But I am all for trying it
>>> if anyone more familiar with the code is fine with it.
>> I see. Well, I suppose we need Ack-s from tty/serial/8250 maintainers.
>> I would not be very happy if _only_ printk people Ack the patch.
FWIW, the lockdep trace is not seen anymore with the patch applied.
Regards,
Shirish S
> This conditional disable for irq_shared does not look nice to me
> from the other device point of view :)
>
> Would it be possible to just set up te dummy interrupt handler
> for the startup, then change it back afterwards? See for example
> omap8250_no_handle_irq().
>
> The other device for irq_shared should be capable of dealing
> with spurious interrupts if it's shared.
>
> Regards,
>
> Tony
--
Regards,
Shirish S
next prev parent reply other threads:[~2020-07-01 6:43 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 17:30 UART/TTY console deadlock Raul Rangel
2020-06-22 17:37 ` Andy Shevchenko
2020-06-30 3:58 ` Sergey Senozhatsky
2020-06-30 10:21 ` Petr Mladek
2020-06-30 10:55 ` Sergey Senozhatsky
2020-06-30 11:40 ` Andy Shevchenko
2020-06-30 12:22 ` Petr Mladek
2020-06-30 13:05 ` Sergey Senozhatsky
2020-06-30 18:02 ` Tony Lindgren
2020-07-01 6:44 ` S, Shirish [this message]
2020-07-02 3:48 ` S, Shirish
2020-07-02 6:11 ` Greg Kroah-Hartman
2020-07-02 6:14 ` S, Shirish
2020-07-02 6:34 ` Sergey Senozhatsky
2020-07-02 7:11 ` Greg Kroah-Hartman
2020-07-02 5:12 ` Sergey Senozhatsky
2020-07-02 5:40 ` Sergey Senozhatsky
2020-07-02 8:20 ` Andy Shevchenko
2020-07-03 10:53 ` Sergey Senozhatsky
2020-07-04 11:37 ` Andy Shevchenko
2020-07-02 16:05 ` Tony Lindgren
2020-07-03 10:32 ` Sergey Senozhatsky
2020-07-04 11:35 ` Andy Shevchenko
2020-07-04 11:59 ` Andy Shevchenko
2020-07-06 11:31 ` Kurt Kanzenbach
2020-07-06 14:43 ` Sergey Senozhatsky
2020-07-08 7:40 ` Kurt Kanzenbach
2020-07-08 8:07 ` Sergey Senozhatsky
2020-07-08 9:52 ` Petr Mladek
2020-07-09 13:22 ` Sergey Senozhatsky
2020-07-14 16:16 ` Raul Rangel
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