On Mon, 22 Jul 2002, Oleg Nesterov wrote:
> Note that smp_xxx_interrupt() functions must be carefull
> with preemt_{disable,enable} brackets.
>
> For example, smp_invalidate_interrupt() may be preempted
> after put_cpu(). Probably not big deal (it is return path),
> but it is better to use preempt_enable_no_resched() here -
> let ret_from_intr: do its job.
i solved it slightly differently: added a new put_cpu_no_resched() macro.
> smp_{error,spurious,thermal}_interrupt() - all of them
> use printk() without bumping preemt_count and have problem
> after spin_unlock_irqrestore(&logbuf_lock, flags).
fixed this - all these IRQ vector paths must use irq_enter()/irq_exit()
pairs.
> If these problems worth fixing, then preempt_stop (cli) can be killed in
> entry.S:ret_from_intr(), yes? If i understand correctly none of the irq
> handlers should return to low level code with irq enabled.
yes, it can be removed, and i did this.
> May I suggest somebody with good english fix
> Documentation/preempt-locking.txt?
> It states, that disabled interrupts prevents preemption.
> Yes, but only in a sense, that the delivery of reschedule
> interrupt is suppressed.
>
> Process with irqs disabled and current->preempt_count == 0 can
> be preempted (with interrupts enabled) after spin_lock/unlock etc.
> Even in UP case preemption can happen while calling wake_up_...().
added such a section to preempt-locking.txt.
this and the other changes can be found at:
http://redhat.com/~mingo/remove-irqlock-patches/remove-irqlock-2.5.27-D9
is anything else missing?
Ingo
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This archive was generated by hypermail 2b29 : Tue Jul 23 2002 - 22:00:39 EST