From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>, Petr Mladek <pmladek@suse.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: Sat, 4 Jul 2020 14:35:46 +0300 [thread overview]
Message-ID: <CAHp75VdvNi_LWv7QhEsm1vQikeiMpi68qmCwoVttjnp7oq0ahg@mail.gmail.com> (raw)
In-Reply-To: <20200703103241.GB182102@jagdpanzerIV.localdomain>
On Fri, Jul 3, 2020 at 1:32 PM Sergey Senozhatsky
<sergey.senozhatsky@gmail.com> wrote:
>
> On (20/07/02 09:05), Tony Lindgren wrote:
> > * Sergey Senozhatsky <sergey.senozhatsky@gmail.com> [200702 05:13]:
> > > On (20/06/30 11:02), Tony Lindgren wrote:
> > > > 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().
> > >
> > > I think we can do it. serial8250_do_startup() and irq handler take
> > > port->lock, so they should be synchronized.
> > >
> > > Something like this then?
> >
> > Yeah thanks this should work better for shared irq.
>
> This is, basically, an equivalent of
>
> ---
> drivers/tty/serial/8250/8250_port.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index d64ca77d9cfa..dba7747d2ddd 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2275,6 +2275,7 @@ int serial8250_do_startup(struct uart_port *port)
>
> if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {
> unsigned char iir1;
> +
> /*
> * Test for UARTs that do not reassert THRE when the
> * transmitter is idle and the interrupt has already
> @@ -2284,8 +2285,6 @@ 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);
> @@ -2297,8 +2296,6 @@ 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);
>
> /*
...which effectively is a revert of
768aec0b5bcc ("serial: 8250: fix shared interrupts issues with SMP and
RT kernels")
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-07-04 11:36 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
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 [this message]
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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