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

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Message-ID: <651a8488-caec-b153-43c7-1fb81f641f1a@gmail.com>
Date:   Sat, 13 Oct 2018 11:21:46 -0700
From:   Frank Rowand <frowand.list@...il.com>
To:     Joe Perches <joe@...ches.com>, Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        devicetree@...r.kernel.org, linux-fpga@...r.kernel.org
Subject: Re: [PATCH v2 12/18] of: overlay: check prevents multiple fragments
 add or delete same node

On 10/13/18 05:51, Joe Perches wrote:
> On Fri, 2018-10-12 at 21:53 -0700, frowand.list@...il.com wrote:
>> From: Frank Rowand <frank.rowand@...y.com>
>>
>> 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@.../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.


> 
>> +						/* 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.

-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;
> 			}
> 		}
> 	}
> 
> 
>