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    SubjectRe: [RFC PATCH v1 00/25] printk: new implementation
    On (02/12/19 15:29), John Ogness wrote:
    > - console_flush_on_panic() currently is a NOP. It is pretty clear how
    > this could be implemented if atomic_write was available. But if no
    > such console is registered, it is not clear what should be done. Is
    > this function really even needed?

    If you now rely on a fully preemptible printk kthread to flush
    pending logbuf messages, then console_flush_on_panic() is your
    only chance to see those pending logbuf messages on the serial
    console when the system dies.

    Non-atomic consoles should become atomic once you call bust_spinlocks(1),
    this is what we currently have:

    panic()
    bust_spinlocks(1) // sets oops_in_progress
    console_flush_on_panic()
    call_console_drivers()
    -> serial_driver_write()
    if (oops_in_progress)
    locked = spin_trylock_irqsave(&port->lock);
    uart_console_write();
    if (locked)
    spin_unlock_irqrestore(&port->lock);

    -ss

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