* Thomas Gleixner <[email protected]> wrote:
> Hmm. That's the code in question:
>
> void __init timekeeping_init(void)
> {
> unsigned long flags;
> unsigned long sec = read_persistent_clock();
>
> write_seqlock_irqsave(&xtime_lock, flags);
>
> The rtc_lock is never taken inside the xtime_lock.
>
> Looks like code reordering due to gcc extra magic. Which compiler ?
i dont think it's due to code reordering. The code that lockdep flagged
is the new code in arch/i386/kernel/bootflag.c, sbf_read() and
sbf_write(). It does:
spin_lock_irqsave(&rtc_lock, flags);
CMOS_WRITE(v, sbf_port);
spin_unlock_irqrestore(&rtc_lock, flags);
and:
spin_lock_irqsave(&rtc_lock, flags);
v = CMOS_READ(sbf_port);
spin_unlock_irqrestore(&rtc_lock, flags);
and is apparently called with the xtime_lock held. Was that code ever
booted with CONFIG_PROVE_LOCKING enabled?
Ingo
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