Re: [Xen-devel] [PATCH] kexec: Add spinlock for the whole hypercall

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Tue, Apr 11, 2017 at 06:31:36AM -0600, Jan Beulich wrote:
> >>> On 11.04.17 at 13:24, <daniel.kiper@xxxxxxxxxx> wrote:
> > On Tue, Apr 11, 2017 at 01:46:37AM -0600, Jan Beulich wrote:
> >> >>> On 10.04.17 at 21:44, <eric.devolder@xxxxxxxxxx> wrote:
> >> wouldn't it be better to handle this with a static state variable,
> >> which gets checked/set atomically, and which if already set simply
> >> leads to a continuation being arranged for?
> >
> > Do you think about something like that:
> >
> > if ( test_bit(KEXEC_FLAG_IN_PROGRESS, &kexec_flags) && 
> > hypercall_preempt_check() )
> >     return hypercall_create_continuation(__HYPERVISOR_kexec_op, "h", uarg);
>
> Well, minus the hypercall_preempt_check() call of course. And I'd

OK.

> expect this to be a test_and_set_bit().

Ahhh... Right.

Eric, please try to fix it as Jan suggested.

Daniel

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