Messages in this thread | | | Date | Thu, 24 Jul 2008 09:12:10 +0200 | Subject | Re: [lockdep warning] INFO: inconsistent lock state, serial8250_interrupt(), &port_lock_key | From | Borislav Petkov <> |
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On Thu, Jul 24, 2008 at 08:53:29AM +0200, Borislav Petkov wrote: > 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.
Actually, this explanation is not correct - it should be more like:
serial8250_startup() doesn't disable interrupts while taking the &up->port.lock which might race against the interrupt handler serial8250_interrupt(), which when entered, will deadlock waiting for the lock to be released.
> > 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.
-- Regards/Gruß, Boris. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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