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    SubjectRe: PPS parport boot lockup: INFO: HARDIRQ-READ-safe -> HARDIRQ-READ-unsafe lock order detected
    В Fri, 21 Jan 2011 08:37:34 -0800
    Linus Torvalds <torvalds@linux-foundation.org> пишет:

    > On Fri, Jan 21, 2011 at 6:44 AM, Alexander Gordeev
    > <lasaine@lvk.cs.msu.su> wrote:
    > >
    > > But parport_unregister_device should probably never be called while
    > > parport interrupts are enabled (in hardware). So this is a false
    > > positive. Is this right?
    >
    > "Enabled in hardware" is immaterial - with shared interrupts, it
    > doesn't matter one whit whether parport interrupts are disabled on the
    > chip, because some other chip may be using the same interrupt line.
    >
    > So you'd need to have something that guarantees that there is no
    > concurrent use, like actually unregistering the irq handler itself.
    > Things like that can work.
    >
    > HOWEVER, even then I think you should see the lockdep message as a
    > problem. The automated toolchain is great because it shows problems
    > that it thinks might happen - not when they happen, but based on a
    > simpler theoretical model. Ignoring the error because there is some
    > rule in place that is hard to explain to the automated toolchain is
    > the wrong thing to do, because it makes the lockdep automation less
    > reliable.
    >
    > Think of it as a compiler warning - maybe the warning doesn't actually
    > imply an actual bug, but you should strive to write code that doesn't
    > warn, because otherwise the noise from the warning you ignored will
    > make it harder for others to see the _real_ bugs.
    >
    > Linus


    Ok, thank you very much for clarification!
    I'll send the patch as reply to the first e-mail.

    --
    Alexander
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