Re: [PATCH v2 12/18] of: overlay: check prevents multiple fragments add or delete same node

From: Frank Rowand
Date: Sun Oct 14 2018 - 20:29:19 EST


On 10/13/18 11:21, Frank Rowand wrote:
> On 10/13/18 05:51, Joe Perches wrote:
>> On Fri, 2018-10-12 at 21:53 -0700, frowand.list@xxxxxxxxx wrote:
>>> From: Frank Rowand <frank.rowand@xxxxxxxx>
>>>
>>> Multiple overlay fragments adding or deleting the same node is not
>>> supported. Replace code comment of such, with check to detect the
>>> attempt and fail the overlay apply.
>>>
>>> Devicetree unittest where multiple fragments added the same node was
>>> added in the previous patch in the series. After applying this patch
>>> the unittest messages will no longer include:
>>>
>>> Duplicate name in motor-1, renamed to "controller#1"
>>> OF: overlay: of_overlay_apply() err=0
>>> ### dt-test ### of_overlay_fdt_apply() expected -22, ret=0, overlay_bad_add_dup_node
>>> ### dt-test ### FAIL of_unittest_overlay_high_level():2419 Adding overlay 'overlay_bad_add_dup_node' failed
>>>
>>> ...
>>>
>>> ### dt-test ### end of unittest - 210 passed, 1 failed
>>>
>>> but will instead include:
>>>
>>> OF: overlay: ERROR: multiple overlay fragments add and/or delete node /testcase-data-2/substation@100/motor-1/controller
>>>
>>> ...
>>>
>>> ### dt-test ### end of unittest - 211 passed, 0 failed
>> []
>>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> []
>>> @@ -523,6 +515,54 @@ static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
>>> }
>>>
>>> /**
>>> + * check_changeset_dup_add_node() - changeset validation: duplicate add node
>>> + * @ovcs: Overlay changeset
>>> + *
>>> + * Check changeset @ovcs->cset for multiple add node entries for the same
>>> + * node.
>>> + *
>>> + * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
>>> + * invalid overlay in @ovcs->fragments[].
>>> + */
>>> +static int check_changeset_dup_add_node(struct overlay_changeset *ovcs)
>>> +{
>>> + struct of_changeset_entry *ce_1, *ce_2;
>>> + char *fn_1, *fn_2;
>>> + int name_match;
>>> +
>>> + list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
>>> +
>>> + if (ce_1->action == OF_RECONFIG_ATTACH_NODE ||
>>> + ce_1->action == OF_RECONFIG_DETACH_NODE) {
>>> +
>>> + ce_2 = ce_1;
>>> + list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
>>> + if (ce_2->action == OF_RECONFIG_ATTACH_NODE ||
>>> + ce_2->action == OF_RECONFIG_DETACH_NODE) {
>>> + /* inexpensive name compare */
>>> + if (!of_node_cmp(ce_1->np->full_name,
>>> + ce_2->np->full_name)) {
>>
>> A bit of odd indentation here.
>> This line is normally aligned to the second ( on the line above.
>
> Yes, thanks.

This line gets joined into a single line in version 3, so I will leave
the bad formatting in patch 12 to make my life easier when moving
to version 3.


>>
>>> + /* expensive full path name compare */
>>> + fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>>> + fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
>>> + name_match = !strcmp(fn_1, fn_2);
>>> + kfree(fn_1);
>>> + kfree(fn_2);
>>> + if (name_match) {
>>> + pr_err("ERROR: multiple overlay fragments add and/or delete node %pOF\n",
>>> + ce_1->np);
>>> + return -EINVAL;
>>> + }
>>> + }
>>> + }
>>> + }
>>> + }
>>> + }
>>> +
>>> + return 0;
>>> +}
>>
>> Style trivia:
>>
>> Using inverted tests and continue would reduce indentation.
>
> Yes, thanks.

In version 3, fixed in patch 13/18 instead of 12/18, where this pattern
has been split into two functions.

-Frank


>
> -Frank
>
>
>>
>> list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
>> if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
>> ce_1->action != OF_RECONFIG_DETACH_NODE)
>> continue;
>>
>> ce_2 = ce_1;
>> list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
>> if (ce_2->action != OF_RECONFIG_ATTACH_NODE &&
>> ce_2->action != OF_RECONFIG_DETACH_NODE)
>> continue;
>>
>> /* inexpensive name compare */
>> if (of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
>> continue;
>>
>> /* expensive full path name compare */
>> fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
>> fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
>> name_match = !strcmp(fn_1, fn_2);
>> kfree(fn_1);
>> kfree(fn_2);
>> if (name_match) {
>> pr_err("ERROR: multiple overlay fragments add and/or delete node %pOF\n",
>> ce_1->np);
>> return -EINVAL;
>> }
>> }
>> }
>>
>>
>>
>
>