On Tue, Jan 12, 2016 at 03:16:15PM +1100, David Gibson wrote:
> On Fri, Jan 08, 2016 at 12:25:14PM +0530, Bharata B Rao wrote:
> > This sync API will be used by the CPU hotplug code to wait for the CPU to
> > completely get removed before flagging the failure to the device_add
> > command.
> >
> > Sync version of this call is needed to correctly recover from CPU
> > realization failures when ->plug() handler fails.
> >
> > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com>
> > Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> > ---
> > cpus.c | 12 ++++++++++++
> > include/qom/cpu.h | 8 ++++++++
> > 2 files changed, 20 insertions(+)
> >
> > diff --git a/cpus.c b/cpus.c
> > index 12374af..c829bd6 100644
> > --- a/cpus.c
> > +++ b/cpus.c
> > @@ -1067,6 +1067,8 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
> > qemu_kvm_wait_io_event(cpu);
> > if (cpu->exit && !cpu_can_run(cpu)) {
> > qemu_kvm_destroy_vcpu(cpu);
> > + cpu->created = false;
> > + qemu_cond_signal(&qemu_cpu_cond);
>
> I know I reviewed this earlier, but I suspect this needs to be
> qemu_cond_broadcast. qemu_cpu_cond is global, so there could (at
> least in theory) be multiple things waiting on it, and we don't know
> which one is waiting on *this* cpu, rather than another one (or on any
> other condition handled by this qemu_cpu_cond).
qemu_cpu_cond condition variable is currently handling the CPU creation
condition where qemu_cond_signal() is being used. From what I understand,
only main thread will be waiting on this condition.
In this patch, I am using the same condition variable to track CPU
deletion condition too. After this too, I think only main thread will be
waiting for the deletion to get completed. So using qemu_cond_signal()
should be ok isn't ?
Regards,
Bharata.
