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SubjectRe: [lockdep warning] INFO: inconsistent lock state, serial8250_interrupt(), &port_lock_key
From
On Wed, Jul 23, 2008 at 11:36:04AM +0200, Ingo Molnar wrote:
>
> * Ingo Molnar <mingo@elte.hu> wrote:
>
> > =================================
> > [ INFO: inconsistent lock state ]
> > 2.6.26-tip-06509-gb4ebc67-dirty #13600
> > ---------------------------------
>
> the upstream component of that is: v2.6.26-6077-gc010b2f
>
> i.e. my suspicion is that this got introduced via the recent tty
> changes.

Hi,

i hit the same warning here. How about the following fix (this is at least what
i think happens):
--

serial8250_startup() might unconditionally enable irqs after releasing
&up->port.lock while we're still servicing an interrupt.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>

--
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 27f34a9..55eca08 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1874,7 +1874,7 @@ static int serial8250_startup(struct uart_port *port)
* the interrupt is enabled. Delays are necessary to
* allow register changes to become visible.
*/
- spin_lock(&up->port.lock);
+ spin_lock_irqsave(&up->port.lock, flags);
if (up->port.flags & UPF_SHARE_IRQ)
disable_irq_nosync(up->port.irq);

@@ -1890,7 +1890,7 @@ static int serial8250_startup(struct uart_port *port)

if (up->port.flags & UPF_SHARE_IRQ)
enable_irq(up->port.irq);
- spin_unlock(&up->port.lock);
+ spin_unlock_irqrestore(&up->port.lock, flags);

/*
* If the interrupt is not reasserted, setup a timer to
--
Regards/Gruß,
Boris.
--
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