On Thu, Jun 22, 2017 at 10:01 PM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> On Thu, 2017-06-22 at 15:44 -0500, Rob Herring wrote:
>> From: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
>>
>> 90% of the usage of device node's full_name is printing it out in a
>> kernel message. However, storing the full path for every node is
>> wasteful and redundant. With a custom format specifier, we can generate
>> the full path at run-time and eventually remove the full path from every
>> node.
>>
>> For instance typical use is:
>> pr_info("Frobbing node %s\n", node->full_name);
>>
>> Which can be written now as:
>> pr_info("Frobbing node %pOF\n", node);
>
> I still think this should use another identifier like
> %pO for object then another letter for type of object
> maybe N for node.
It is. O is for kobj and F is for device node. It doesn't make a much
sense separately, but OF together makes sense as Open Firmware.
>
> And F is flags, f is name
>
>> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> []
>> @@ -1470,6 +1471,131 @@ char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
>> return format_flags(buf, end, flags, names);
>> }
>>
>> +static int device_node_calc_depth(const struct device_node *np)
>> +{
>> + int d;
>> +
>> + for (d = 0; np; d++)
>> + np = np->parent;
>> +
>> + return d;
>> +}
>> +
>> +static noinline_for_stack
>> +char *device_node_gen_full_name(const struct device_node *np, char *buf, char *end)
>> +{
>> + int i;
>> + int depth = device_node_calc_depth(np);
>> + static const struct printf_spec strspec = {
>> + .field_width = -1,
>> + .precision = -1,
>> + };
>> + const struct device_node *nodes[depth];
>> +
>> + if (!depth)
>> + returnuf;
>> + /* special case for root node */
>> + if (depth == 1)
>> + return string(buf, end, "/", strspec);
>> +
>> + depth--;
>> + for (i = depth - 1; i >= 0; i--) {
>> + nodes[i] = np;
>> + np = np->parent;
>> + }
>> + for (i = 0; i < depth; i++) {
>> + buf = string(buf, end, "/", strspec);
>> + buf = string(buf, end, kbasename(nodes[i]->full_name), strspec);
>> + }
>> + return buf;
>> +}
>
> I think there should be another function to get
> a particular struct device_node * at a particular
> depth to avoid all the pointers on stack.
>
> Basically, adapt the for (i = depth - 1 loop to
> a function that returns nodes[i]
Okay.
Rob
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