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    SubjectRe: [patch] Real-Time Preemption, -RT-2.6.9-rc4-mm1-U8

    * Michal Schmidt <xschmi00@stud.feec.vutbr.cz> wrote:

    > That patch was not enough. The BUGs were still showing up the same as
    > before. I tried to debug it myself. I've found an interesting thing in
    > kernel/printk.c:release_console_sem(). There is the following
    > sequence:
    >
    > spin_lock_irqsave(&logbuf_lock, flags);
    > /* ... some code ... */
    > spin_unlock(&logbuf_lock);
    > call_console_drivers(...);
    > local_irq_restore(flags);
    >
    > I know very little about locking, but I didn't like this two-phased
    > unlock. So I replaced it with a single spin_unlock_irqrestore. Patch
    > attached. I'm almost certain that there is a reason for the two-phased
    > unlocking and that this patch will break something, but so far it
    > works for me. netconsole now works without complaining.

    ah, indeed. Note that this is still not enough - please try to add a
    local_irq_enable() to netconsole.c's console-write function - does that
    fix it equally well for you?

    the reason is that if we crash within an irqs-off section then
    netconsole will still be called with interrupts disabled and will
    trigger the assert.

    Ingo
    -
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