On Monday 06 February 2006 22:36, Ingo Molnar wrote:
>
> * Andi Kleen <[email protected]> wrote:
>
> > Index: linux-2.6.15/lib/spinlock_debug.c
> > ===================================================================
> > --- linux-2.6.15.orig/lib/spinlock_debug.c
> > +++ linux-2.6.15/lib/spinlock_debug.c
> > @@ -68,13 +68,13 @@ static inline void debug_spin_unlock(spi
> > static void __spin_lock_debug(spinlock_t *lock)
> > {
> > int print_once = 1;
> > - u64 i;
> >
> > for (;;) {
> > - for (i = 0; i < loops_per_jiffy * HZ; i++) {
> > - cpu_relax();
> > + unsigned long timeout = jiffies + HZ;
> > + while (time_before(jiffies, timeout)) {
> > if (__raw_spin_trylock(&lock->raw_lock))
> > return;
> > + cpu_relax();
>
> The reason i added a loop counter was to solve the case where we are
> spinning with interrupts disabled - jiffies wont increase there!
Yes but the NMI watchdog should catch it eventually
[we really should enable it by default on i386 too - local APIC
NMI should work everywhere with APIC]
Oops I missed the write lock case. Thanks.
> a better solution would be to call __delay(1) after the first failed
> attempt, that would make the delay at least 1 second long. It seems
> __delay() is de-facto exported by every architecture, so we can rely on
> it in the global spinlock code.
>
> So how about the patch below instead?
Are you sure loops_per_jiffie is always in delay(1) units?
-Andi
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