On Mon, Feb 01, 2016 at 02:01:09PM +0530, Anshuman Khandual wrote:
> On 01/29/2016 10:54 AM, David Gibson wrote:
>
> > +
> > +static int pseries_lpar_resize_hpt_commit(void *data)
> > +{
> > + struct hpt_resize_state *state = data;
> > +
> > + state->commit_rc = plpar_resize_hpt_commit(0, state->shift);
> > + if (state->commit_rc != H_SUCCESS)
> > + return -EIO;
> > +
> > + /* Hypervisor has transitioned the HTAB, update our globals */
> > + ppc64_pft_size = state->shift;
> > + htab_size_bytes = 1UL << ppc64_pft_size;
> > + htab_hash_mask = (htab_size_bytes >> 7) - 1;
> > +
> > + return 0;
> > +}
> > +
>
> snip
>
> > +/* Must be called in user context */
> > +static int pseries_lpar_resize_hpt(unsigned long shift)
> > +{
> > + struct hpt_resize_state state = {
> > + .shift = shift,
> > + .commit_rc = H_FUNCTION,
>
> > +
> > + rc = stop_machine(pseries_lpar_resize_hpt_commit, &state, NULL);
>
> With my limited knowledge of stop_machine, wondering if the current
> or any future version of 'pseries_lpar_resize_hpt_commit' function
> can cause HPT change (page fault path) while stop is executing it.
It can, but the H_RESIZE_HPT_COMMIT hypercall is synchronous so the
cpu executing it can't make any HPT updates during it. The
stop_machine() prevents any other cpus doing HPT updates.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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