On 07/30, Peter Zijlstra wrote:
>
> On Tue, Jul 21, 2015 at 09:22:47PM +0200, Oleg Nesterov wrote:
>
> > + err = -EDEADLK;
> > + if (stop_work_pending(stopper1) != stop_work_pending(stopper2))
> > + goto unlock;
>
> You could DoS/false positive this by running stop_one_cpu() in a loop
On 07/31, Peter Zijlstra wrote:
>
> + for_each_cpu(cpu, cpumask)
> + arch_spin_lock((arch_spinlock_t *)&per_cpu(cpu_stopper.lock,
> cpu));
> +
> for_each_cpu(cpu, cpumask) {
> work = &per_cpu(cpu_stopper.stop_work, cpu);
> work->fn = fn;
>
On Sat, Aug 01, 2015 at 12:57:18PM +0200, Oleg Nesterov wrote:
> > > + if (stop_work_pending(stopper1) != stop_work_pending(stopper2))
> > > + goto unlock;
> >
> > You could DoS/false positive this by running stop_one_cpu() in a loop,
> > and thereby 'always' having work pending on one but
Hi Peter,
Thanks for looking. I'll try to reply on Monday, just one note...
On 07/30, Peter Zijlstra wrote:
>
> On Tue, Jul 21, 2015 at 09:22:47PM +0200, Oleg Nesterov wrote:
>
> > +static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
> > + int
On Fri, Jul 31, 2015 at 01:12:46PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 30, 2015 at 11:55:27PM +0200, Peter Zijlstra wrote:
> >
> > Exclusion between stop_{one,two}_cpu{,s}() and stop_cpus() makes this
> > trivially go away.
> >
> > Paul's RCU branch already kills try_stop_cpus() dead, so t
On Thu, Jul 30, 2015 at 11:55:27PM +0200, Peter Zijlstra wrote:
>
> Exclusion between stop_{one,two}_cpu{,s}() and stop_cpus() makes this
> trivially go away.
>
> Paul's RCU branch already kills try_stop_cpus() dead, so that wart is
> also gone. But we're still stuck with stop_machine_from_inacti
On Tue, Jul 21, 2015 at 09:22:47PM +0200, Oleg Nesterov wrote:
> +static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
> + int cpu2, struct cpu_stop_work *work2)
> +{
> + struct cpu_stopper *stopper1 = per_cpu_ptr(&cpu_stopper, cpu1);
> +
stop_two_cpus() and stop_cpus() use stop_cpus_lock to avoid the
deadlock, we need to ensure that the stopper functions can't be
queued "backwards" from one another.
Instead, we can change stop_two_cpus() to take 2 stopper->lock's
and queue both works "atomically"; just we need to check that both
-
8 matches
Mail list logo
