[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Simon Kagstrom]

The console hangs during bootup when disable_irq is called from the
transmit interrupt handler (it will wait forever for it's "own"
interrupt in synchronize_irq). Fix by using disable_irq_nosync()
instead.

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
---
Russell: This patch is a bit of RFC since I'm not quite sure that it's the correct
solution. It unbreaks booting on our footbridge-based platform. Let me
know if I should look at other solutions!

 drivers/serial/21285.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/21285.c b/drivers/serial/21285.c
index 1e3d193..8681f13 100644
--- a/drivers/serial/21285.c
+++ b/drivers/serial/21285.c
@@ -58,7 +58,7 @@ static const char serial21285_name[] = "Footbridge UART";
 static void serial21285_stop_tx(struct uart_port *port)
 {
 	if (tx_enabled(port)) {
-		disable_irq(IRQ_CONTX);
+		disable_irq_nosync(IRQ_CONTX);
 		tx_enabled(port) = 0;
 	}
 }
@@ -74,7 +74,7 @@ static void serial21285_start_tx(struct uart_port *port)
 static void serial21285_stop_rx(struct uart_port *port)
 {
 	if (rx_enabled(port)) {
-		disable_irq(IRQ_CONRX);
+		disable_irq_nosync(IRQ_CONRX);
 		rx_enabled(port) = 0;
 	}
 }
-- 
1.6.0.4

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Russell King - ARM Linux]

On Fri, Nov 13, 2009 at 09:02:34AM +0100, Simon Kagstrom wrote:
> Russell: This patch is a bit of RFC since I'm not quite sure that it's
> the correct solution. It unbreaks booting on our footbridge-based
> platform. Let me know if I should look at other solutions!

It does look like the right thing to do - the original code will hang
now that we're using genirq stuff.

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Simon Kagstrom]

On Fri, 13 Nov 2009 09:59:37 +0000
Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:

> On Fri, Nov 13, 2009 at 09:02:34AM +0100, Simon Kagstrom wrote:
> > Russell: This patch is a bit of RFC since I'm not quite sure that it's
> > the correct solution. It unbreaks booting on our footbridge-based
> > platform. Let me know if I should look at other solutions!
> 
> It does look like the right thing to do - the original code will hang
> now that we're using genirq stuff.

Good, thanks. I guess you'll take it into your tree then?

// Simon

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Ben Dooks]

On Fri, Nov 13, 2009 at 09:02:34AM +0100, Simon Kagstrom wrote:
> The console hangs during bootup when disable_irq is called from the
> transmit interrupt handler (it will wait forever for it's "own"
> interrupt in synchronize_irq). Fix by using disable_irq_nosync()
> instead.
> 
> Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Acked-by: Ben Dooks <ben@simtec.co.uk>
> ---
> Russell: This patch is a bit of RFC since I'm not quite sure that it's the correct
> solution. It unbreaks booting on our footbridge-based platform. Let me
> know if I should look at other solutions!
> 
>  drivers/serial/21285.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/serial/21285.c b/drivers/serial/21285.c
> index 1e3d193..8681f13 100644
> --- a/drivers/serial/21285.c
> +++ b/drivers/serial/21285.c
> @@ -58,7 +58,7 @@ static const char serial21285_name[] = "Footbridge UART";
>  static void serial21285_stop_tx(struct uart_port *port)
>  {
>  	if (tx_enabled(port)) {
> -		disable_irq(IRQ_CONTX);
> +		disable_irq_nosync(IRQ_CONTX);
>  		tx_enabled(port) = 0;
>  	}
>  }
> @@ -74,7 +74,7 @@ static void serial21285_start_tx(struct uart_port *port)
>  static void serial21285_stop_rx(struct uart_port *port)
>  {
>  	if (rx_enabled(port)) {
> -		disable_irq(IRQ_CONRX);
> +		disable_irq_nosync(IRQ_CONRX);
>  		rx_enabled(port) = 0;
>  	}
>  }
> -- 
> 1.6.0.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Simon Kagstrom]

Hi again Russell!

On Fri, 13 Nov 2009 09:59:37 +0000
Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:

> On Fri, Nov 13, 2009 at 09:02:34AM +0100, Simon Kagstrom wrote:
> > Russell: This patch is a bit of RFC since I'm not quite sure that it's
> > the correct solution. It unbreaks booting on our footbridge-based
> > platform. Let me know if I should look at other solutions!
> 
> It does look like the right thing to do - the original code will hang
> now that we're using genirq stuff.

I haven't see this patch in 2.6.33 yet, was it forgotten or is it still
in the queue somewhere?

(Ping!)

// Simon

[PATCH] serial21285: fix disable_irq-from-interrupt-handler deadlock

[Russell King - ARM Linux]

On Thu, Dec 17, 2009 at 08:51:42AM +0100, Simon Kagstrom wrote:
> Hi again Russell!
> 
> On Fri, 13 Nov 2009 09:59:37 +0000
> Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> 
> > On Fri, Nov 13, 2009 at 09:02:34AM +0100, Simon Kagstrom wrote:
> > > Russell: This patch is a bit of RFC since I'm not quite sure that it's
> > > the correct solution. It unbreaks booting on our footbridge-based
> > > platform. Let me know if I should look at other solutions!
> > 
> > It does look like the right thing to do - the original code will hang
> > now that we're using genirq stuff.
> 
> I haven't see this patch in 2.6.33 yet, was it forgotten or is it still
> in the queue somewhere?
> 
> (Ping!)

It needs to go into the patch system; I'm terrible with taking patches
directly from email.

Just add a 'KernelVersion:' tag to indicate which version the patch was
generated against somewhere in the patch description and forward to
patches at arm.linux.org.uk