Re: [PATCH v6 38/42] drivers/of: Unflatten subordinate nodes after specified level

Rob Herring
2015-08-06T14:09:11Z

On Wed, Aug 5, 2015 at 11:11 PM, Gavin Shan <gwshan@linux.vnet.ibm.com> wrote:
> unflatten_dt_node() is called recursively to unflatten FDT nodes
> with the assumption that FDT blob has only one root node, which
> isn't true when the FDT blob represents device sub-tree. This
> improves the function to supporting device sub-tree that have
> multiple nodes in the first level:
>
> * Rename original unflatten_dt_node() to __unflatten_dt_node().
> * Wrapper unflatten_dt_node() calls __unflatten_dt_node() with
> adjusted current node depth to 1 to avoid underflow.
>
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

Acked-by: Rob Herring <robh@kernel.org>

> ---
> drivers/of/fdt.c | 53 ++++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 40 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 0749656..a18a2ce 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -161,7 +161,7 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
> }
>
> /**
> - * unflatten_dt_node - Alloc and populate a device_node from the flat tree
> + * __unflatten_dt_node - Alloc and populate a device_node from the flat tree
> * @blob: The parent device tree blob
> * @mem: Memory chunk to use for allocating device nodes and properties
> * @poffset: pointer to node in flat tree
> @@ -171,20 +171,20 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
> * @dryrun: If true, do not allocate device nodes but still calculate needed
> * memory size
> */
> -static void * unflatten_dt_node(const void *blob,
> +static void *__unflatten_dt_node(const void *blob,
> void *mem,
> int *poffset,
> struct device_node *dad,
> struct device_node **nodepp,
> unsigned long fpsize,
> - bool dryrun)
> + bool dryrun,
> + int *depth)
> {
> const __be32 *p;
> struct device_node *np;
> struct property *pp, **prev_pp = NULL;
> const char *pathp;
> unsigned int l, allocl;
> - static int depth = 0;
> int old_depth;
> int offset;
> int has_name = 0;
> @@ -337,13 +337,25 @@ static void * unflatten_dt_node(const void *blob,
> np->type = "<NULL>";
> }
>
> - old_depth = depth;
> - *poffset = fdt_next_node(blob, *poffset, &depth);
> - if (depth < 0)
> - depth = 0;
> - while (*poffset > 0 && depth > old_depth)
> - mem = unflatten_dt_node(blob, mem, poffset, np, NULL,
> - fpsize, dryrun);
> + /* Multiple nodes might be in the first depth level if
> + * the device tree is sub-tree. All nodes in current
> + * or deeper depth are unflattened after it returns.
> + */
> + old_depth = *depth;
> + *poffset = fdt_next_node(blob, *poffset, depth);
> + while (*poffset > 0) {
> + if (*depth < old_depth)
> + break;
> +
> + if (*depth == old_depth)
> + mem = __unflatten_dt_node(blob, mem, poffset,
> + dad, NULL, fpsize,
> + dryrun, depth);
> + else if (*depth > old_depth)
> + mem = __unflatten_dt_node(blob, mem, poffset,
> + np, NULL, fpsize,
> + dryrun, depth);
> + }
>
> if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
> pr_err("unflatten: error %d processing FDT\n", *poffset);
> @@ -369,6 +381,20 @@ static void * unflatten_dt_node(const void *blob,
> return mem;
> }
>
> +static void *unflatten_dt_node(const void *blob,
> + void *mem,
> + int *poffset,
> + struct device_node *dad,
> + struct device_node **nodepp,
> + bool dryrun)
> +{
> + int depth = 1;
> +
> + return __unflatten_dt_node(blob, mem, poffset,
> + dad, nodepp, 0,
> + dryrun, &depth);
> +}
> +
> /**
> * __unflatten_device_tree - create tree of device_nodes from flat blob
> *
> @@ -408,7 +434,8 @@ static void __unflatten_device_tree(const void *blob,
>
> /* First pass, scan for size */
> start = 0;
> - size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0, true);
> + size = (unsigned long)unflatten_dt_node(blob, NULL, &start,
> + NULL, NULL, true);
> size = ALIGN(size, 4);
>
> pr_debug(" size is %lx, allocating...\n", size);
> @@ -423,7 +450,7 @@ static void __unflatten_device_tree(const void *blob,
>
> /* Second pass, do actual unflattening */
> start = 0;
> - unflatten_dt_node(blob, mem, &start, NULL, mynodes, 0, false);
> + unflatten_dt_node(blob, mem, &start, NULL, mynodes, false);
> if (be32_to_cpup(mem + size) != 0xdeadbeef)
> pr_warning("End of tree marker overwritten: %08x\n",
> be32_to_cpup(mem + size));
> --
> 2.1.0
>