* [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown()
@ 2022-05-10 13:54 Thomas Pfaff
2022-05-10 17:44 ` Thomas Gleixner
2022-05-11 6:21 ` Jiri Slaby
0 siblings, 2 replies; 4+ messages in thread
From: Thomas Pfaff @ 2022-05-10 13:54 UTC (permalink / raw)
To: Greg Kroah-Hartman, Jiri Slaby; +Cc: Thomas Gleixner, linux-kernel
From: Thomas Pfaff <tpfaff@pcs.com>
Calling synchronize_irq() after free_irq() is pointless, the context to
the irq is already lost.
It was noticed while creating the bugfix "genirq: Synchronize interrupt
thread startup".
Signed-off-by: Thomas Pfaff <tpfaff@pcs.com>
---
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 57840cf90388..b76e76e650ba 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1704,12 +1704,6 @@ static void uart_port_shutdown(struct tty_port *port)
*/
if (uport)
uport->ops->shutdown(uport);
-
- /*
- * Ensure that the IRQ handler isn't running on another CPU.
- */
- if (uport)
- synchronize_irq(uport->irq);
}
static int uart_carrier_raised(struct tty_port *port)
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown()
2022-05-10 13:54 [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown() Thomas Pfaff
@ 2022-05-10 17:44 ` Thomas Gleixner
2022-05-11 6:21 ` Jiri Slaby
1 sibling, 0 replies; 4+ messages in thread
From: Thomas Gleixner @ 2022-05-10 17:44 UTC (permalink / raw)
To: Thomas Pfaff, Greg Kroah-Hartman, Jiri Slaby; +Cc: linux-kernel
On Tue, May 10 2022 at 15:54, Thomas Pfaff wrote:
> From: Thomas Pfaff <tpfaff@pcs.com>
>
> Calling synchronize_irq() after free_irq() is pointless, the context to
> the irq is already lost.
> It was noticed while creating the bugfix "genirq: Synchronize interrupt
> thread startup".
>
> Signed-off-by: Thomas Pfaff <tpfaff@pcs.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown()
2022-05-10 13:54 [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown() Thomas Pfaff
2022-05-10 17:44 ` Thomas Gleixner
@ 2022-05-11 6:21 ` Jiri Slaby
2022-05-11 7:48 ` Thomas Pfaff
1 sibling, 1 reply; 4+ messages in thread
From: Jiri Slaby @ 2022-05-11 6:21 UTC (permalink / raw)
To: Thomas Pfaff, Greg Kroah-Hartman; +Cc: Thomas Gleixner, linux-kernel
On 10. 05. 22, 15:54, Thomas Pfaff wrote:
> From: Thomas Pfaff <tpfaff@pcs.com>
>
> Calling synchronize_irq() after free_irq() is pointless, the context to
> the irq is already lost.
> It was noticed while creating the bugfix "genirq: Synchronize interrupt
> thread startup".
That's correct for most drivers. But some drivers don't call free_irq()
in ->shutdown(). So you likely have to move the synchronization to them.
By a quick grep, I found icom, jsm, sccnxp, sifive, sunhv, and sunzilog.
> Signed-off-by: Thomas Pfaff <tpfaff@pcs.com>
> ---
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 57840cf90388..b76e76e650ba 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1704,12 +1704,6 @@ static void uart_port_shutdown(struct tty_port *port)
> */
> if (uport)
> uport->ops->shutdown(uport);
> -
> - /*
> - * Ensure that the IRQ handler isn't running on another CPU.
> - */
> - if (uport)
> - synchronize_irq(uport->irq);
> }
>
> static int uart_carrier_raised(struct tty_port *port)
>
>
--
js
suse labs
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown()
2022-05-11 6:21 ` Jiri Slaby
@ 2022-05-11 7:48 ` Thomas Pfaff
0 siblings, 0 replies; 4+ messages in thread
From: Thomas Pfaff @ 2022-05-11 7:48 UTC (permalink / raw)
To: Jiri Slaby; +Cc: Greg Kroah-Hartman, Thomas Gleixner, linux-kernel
On Wed, 11 May 2022, Jiri Slaby wrote:
> On 10. 05. 22, 15:54, Thomas Pfaff wrote:
> > From: Thomas Pfaff <tpfaff@pcs.com>
> >
> > Calling synchronize_irq() after free_irq() is pointless, the context to
> > the irq is already lost.
> > It was noticed while creating the bugfix "genirq: Synchronize interrupt
> > thread startup".
>
> That's correct for most drivers. But some drivers don't call free_irq() in
> ->shutdown(). So you likely have to move the synchronization to them. By a
> quick grep, I found icom, jsm, sccnxp, sifive, sunhv, and sunzilog.
>
Sorry, I did not check all the drivers.
Then I would keep it in serial_core, as it does not hurt anymore.
Thanks,
Thomas
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-05-11 7:48 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2022-05-10 13:54 [PATCH] tty: Remove pointless synchronize_irq() in uart_port_shutdown() Thomas Pfaff
2022-05-10 17:44 ` Thomas Gleixner
2022-05-11 6:21 ` Jiri Slaby
2022-05-11 7:48 ` Thomas Pfaff
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