On 10/10/19 11:56 AM, Nathan Lynch wrote:
> Hi Tyrel,
>
> Tyrel Datwyler <tyr...@linux.ibm.com> writes:
>> +static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
>> +{
>> + const __be32 *indexes;
>> + int i;
>> +
>> + if (of_find_property(parent, "ibm,drc-info", NULL))
>> + return drc_info_valid_index(parent, drc_index);
>> +
>> + indexes = of_get_property(parent, "ibm,drc-indexes", NULL);
>> + if (!indexes)
>> + return false;
>> +
>> + for (i = 0; i < indexes[0]; i++) {
>
> should this be:
>
> for (i = 0; i < be32_to_cpu(indexes[0]); i++) {
> ?
Yes!
>
>
>> + if (be32_to_cpu(indexes[i + 1]) == drc_index)
>> + return true;
>> + }
>> +
>> + return false;
>> }
>
> It looks like this rewrites valid_cpu_drc_index()'s existing code for
> parsing ibm,drc-indexes but I don't see the need for this.
>
> This patch would be easier to review if that were dropped or split out.
Yeah, I'll split it out. There are multiple places where we iterate over the
drc_indexes, and it is implemented several different ways. I basically picked an
implementation to use across the board. I think a better way would be just to
implement a for_each_drc_index(dn, drc_index) macro to abstract away iterator
implementation.
>
>>
>> static ssize_t dlpar_cpu_add(u32 drc_index)
>> @@ -720,8 +756,11 @@ static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
>> static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
>> {
>> struct device_node *parent;
>> + struct property *info;
>> + const __be32 *indexes;
>> int cpus_found = 0;
>> - int index, rc;
>> + int i, j;
>> + u32 drc_index;
>>
>> parent = of_find_node_by_path("/cpus");
>> if (!parent) {
>> @@ -730,24 +769,46 @@ static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32
>> cpus_to_add)
>> return -1;
>> }
>>
>> - /* Search the ibm,drc-indexes array for possible CPU drcs to
>> - * add. Note that the format of the ibm,drc-indexes array is
>> - * the number of entries in the array followed by the array
>> - * of drc values so we start looking at index = 1.
>> - */
>> - index = 1;
>> - while (cpus_found < cpus_to_add) {
>> - u32 drc;
>> + info = of_find_property(parent, "ibm,drc-info", NULL);
>> + if (info) {
>> + struct of_drc_info drc;
>> + const __be32 *value;
>> + int count;
>>
>> - rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
>> - index++, &drc);
>> - if (rc)
>> - break;
>> + value = of_prop_next_u32(info, NULL, &count);
>> + if (value)
>> + value++;
>>
>> - if (dlpar_cpu_exists(parent, drc))
>> - continue;
>> + for (i = 0; i < count; i++) {
>> + of_read_drc_info_cell(&info, &value, &drc);
>> + if (strncmp(drc.drc_type, "CPU", 3))
>> + break;
>> +
>> + for (j = 0; j < drc.num_sequential_elems; j++) {
>> + drc_index = drc.drc_index_start +
>> (drc.sequential_inc * j);
>> +
>> + if (dlpar_cpu_exists(parent, drc_index))
>> + continue;
>>
>> - cpu_drcs[cpus_found++] = drc;
>> + cpu_drcs[cpus_found++] = drc_index;
>
> I am failing to see how this loop is limited by the cpus_to_add
> parameter as it was before this change. It looks like this will overflow
> the cpu_drcs array when cpus_to_add is less than the number of cpus
> found.
You are right. The code is picking every non-present drc_index which will
overflow the supplied buffer as you stated when there are more available indexes
than requested cpus. Will fix to bound the search.
>
> As an aside I don't understand how the add_by_count()/dlpar_cpu_exists()
> algorithm could be correct as it currently stands. It seems to pick the
> first X indexes for which a corresponding cpu node is absent, but that
> set of indexes does not necessarily match the set that is available to
> configure. Something to address separately I suppose.
I'm not sure I follow?
>
>> + }
>> + }
>> + } else {
>> + indexes = of_get_property(parent, "ibm,drc-indexes", NULL);
>> +
>> + /* Search the ibm,drc-indexes array for possible CPU drcs to
>> + * add. Note that the format of the ibm,drc-indexes array is
>> + * the number of entries in the array followed by the array
>> + * of drc values so we start looking at index = 1.
>> + */
>> + for (i = 1; i < indexes[0]; i++) {
>> + drc_index = be32_to_cpu(indexes[i]);
>> +
>> + if (dlpar_cpu_exists(parent, drc_index))
>> + continue;
>> +
>> + cpu_drcs[cpus_found++] = drc_index;
>> + }
>> }
>
> As above, not sure why this was rewritten, and similar comments as
> before apply.
>
Again, wanted to use a single implementation everywere. Obviously, as pointed
out in the previous comment missed a byte swap. Will split out into a separate
patch for consideration.
-Tyrel
