Firstly, who come a patch that is grubbing around in kernel/locking/ has an x86/hyperv subject and isn't Cc'ed to the locking maintainers?
On Mon, Oct 22, 2018 at 12:31:45PM -0400, Waiman Long wrote: > On 10/22/2018 03:32 AM, Juergen Gross wrote: > > On 22/10/2018 03:53, Yi Sun wrote: > >> On 18-10-19 16:20:52, Juergen Gross wrote: > >>> On 19/10/2018 15:13, Yi Sun wrote: > >> [...] > >> > >>>> diff --git a/kernel/locking/qspinlock_paravirt.h > >>>> b/kernel/locking/qspinlock_paravirt.h > >>>> index 0130e48..9e88c7e 100644 > >>>> --- a/kernel/locking/qspinlock_paravirt.h > >>>> +++ b/kernel/locking/qspinlock_paravirt.h > >>>> @@ -7,6 +7,8 @@ > >>>> #include <linux/bootmem.h> > >>>> #include <linux/debug_locks.h> > >>>> > >>>> +#include <asm/mshyperv.h> > >>>> + > >>>> /* > >>>> * Implement paravirt qspinlocks; the general idea is to halt the vcpus > >>>> instead > >>>> * of spinning them. > >>>> @@ -305,6 +307,10 @@ static void pv_wait_node(struct mcs_spinlock *node, > >>>> struct mcs_spinlock *prev) > >>>> wait_early = true; > >>>> break; > >>>> } > >>>> +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) && > >>>> IS_ENABLED(CONFIG_HYPERV) > >>>> + if (!hv_notify_long_spin_wait(SPIN_THRESHOLD - > >>>> loop)) > >>>> + break; > >>>> +#endif Secondly; how come you thought that was acceptable in any way shape or form? > > vcpu_is_preempted() is already part of this loop. And this is a paravirt > > hook. Can't you make use of that? This might require adding another > > parameter to this hook, but I'd prefer that over another pv-spinlock > > hook. > I agree with Juergen on that. I would suggest rename the > vcpu_is_preempted hook into a more generic vcpu_stop_spinning, perhaps, > so different hypervisors can act on the information accordingly. Adding > an extra parameter is fine. No; no extra parameters. vcpu_is_preempted() is a simple and intuitive interface. Why would we want to make it complicated?
