On Tue, 18 Oct 2005, Eric W. Biederman wrote:
> Andy Isaacson <[email protected]> writes:
>
> > +static __init void nmi_cpu_busy(void *data)
> > +{
> > + volatile int *endflag = data;
> > + local_irq_enable();
> > + while (*endflag == 0)
> > + barrier();
> > +}
> > static int __init check_nmi_watchdog(void)
> > {
> > + volatile int endflag = 0;
> > ...
> > + if (nmi_watchdog == NMI_LOCAL_APIC)
> > + smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
> > ...
> > + endflag = 1;
> > printk("OK.\n");
> > if (nmi_watchdog == NMI_LOCAL_APIC)
> > nmi_hz = 1;
> > + kfree(prev_nmi_count);
> > return 0;
> > }
>
> Probably a counter, to ensure the code exits. The code prints
Why not just use the 'wait' variable to smp_call_function to at least
ensure that the lifetime of endflag isn't exceeded? Something like;
static __init void nmi_cpu_busy(void *data)
{
volatile int *endflag = data;
local_irq_enable();
while (*endflag == 0) {
cpu_relax();
rmb();
}
}
static int __init check_nmi_watchdog(void)
{
volatile int endflag = 0;
...
if (nmi_watchdog == NMI_LOCAL_APIC)
smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 1);
...
endflag = 1;
wmb();
Thanks,
Zwane
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