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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

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.