Re: [PATCH] spapr_numa.c: fixes in spapr_numa_FORM2_write_rtas_tables()

[Philippe Mathieu-Daudé]

On 9/22/21 13:52, Greg Kurz wrote:
> On Wed, 22 Sep 2021 13:17:32 +0200
> Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
>
> > On 9/21/21 21:43, Daniel Henrique Barboza wrote:
> > > This patch has a handful of modifications for the recent added
> > > FORM2 support:
> > >
> > > - there is no particular reason for both 'lookup_index_table' and
> > > 'distance_table' to be allocated in the heap, since their sizes are
> > > known right at the start of the function. Use static allocation in
> > > them to spare a couple of g_new0() calls;
> > >
> > > - to not allocate more than the necessary size in 'distance_table'. At
> > > this moment the array is oversized due to allocating uint32_t for all
> > > elements, when most of them fits in an uint8_t;
> > >
> > > - create a NUMA_LOCAL_DISTANCE macro to avoid hardcoding the local
> > > distance value.
> > >
> > > Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> > > ---
> > >    hw/ppc/spapr_numa.c | 35 +++++++++++++++++++----------------
> > >    1 file changed, 19 insertions(+), 16 deletions(-)

> > >    /*
> > >     * Retrieves max_dist_ref_points of the current NUMA affinity.
> > >     */
> > > @@ -500,17 +503,21 @@ static void 
> > > spapr_numa_FORM2_write_rtas_tables(SpaprMachineState *spapr,
> > >        MachineState *ms = MACHINE(spapr);
> > >        NodeInfo *numa_info = ms->numa_state->nodes;
> > >        int nb_numa_nodes = ms->numa_state->num_nodes;
> > > +    /* Lookup index table has an extra uint32_t with its length */
> > > +    uint32_t lookup_index_table[nb_numa_nodes + 1];
> > >        int distance_table_entries = nb_numa_nodes * nb_numa_nodes;
> > > -    g_autofree uint32_t *lookup_index_table = NULL;
> > > -    g_autofree uint32_t *distance_table = NULL;
> > > -    int src, dst, i, distance_table_size;
> > > -    uint8_t *node_distances;
> >
> > This should have be of ptrdiff_t type.
>
> Why ? I don't see pointer subtraction in the code.

Oops, you are right.