drivers/of: Fix build warning in populate_node()

Function populate_node() is used to unflatten FDT blob to device
tree. It supports maximal 64 level of device nodes. There is one
array @fpsizes[64] tracking the full name length of last unflattened
device node in the corresponding level (index of element in the
array - 1). Build warning is seen with CONFIG_FRAME_WARN=1024 like
below on ARM64 as Geert reported. The issue can be reproduced on
PPC64 as well.

  $ make drivers/of/fdt.o
  drivers/of/fdt.c:443:1: warning: the frame size of 1136 bytes is \
  larger than 1024 bytes [-Wframe-larger-than=]

This changes the data type of @fpsizes[i] from "unsigned long" to
"unsigned int" to avoid the build warning. The return value type
of populate_node() and its @fpsize argument is adjusted accordingly.
With this applied, 256 bytes saved from the stack frame on ARM64 and
PPC64 platforms and the above warning isn't seen.

Fixes: 50800082f176 ("drivers/of: Avoid recursively calling unflatten_dt_node()")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index b352f67d710b35eb4c9c51cb814f1bdaeeac456f..14f2f8c7c2607e603337b30a37117195f95f0880 100644 (file)
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -264,13 +264,13 @@ static void populate_properties(const void *blob,
                *pprev = NULL;
 }
 
-static unsigned long populate_node(const void *blob,
-                                  int offset,
-                                  void **mem,
-                                  struct device_node *dad,
-                                  unsigned long fpsize,
-                                  struct device_node **pnp,
-                                  bool dryrun)
+static unsigned int populate_node(const void *blob,
+                                 int offset,
+                                 void **mem,
+                                 struct device_node *dad,
+                                 unsigned int fpsize,
+                                 struct device_node **pnp,
+                                 bool dryrun)
 {
        struct device_node *np;
        const char *pathp;
@@ -397,7 +397,7 @@ static int unflatten_dt_nodes(const void *blob,
        struct device_node *root;
        int offset = 0, depth = 0;
 #define FDT_MAX_DEPTH  64
-       unsigned long fpsizes[FDT_MAX_DEPTH];
+       unsigned int fpsizes[FDT_MAX_DEPTH];
        struct device_node *nps[FDT_MAX_DEPTH];
        void *base = mem;
        bool dryrun = !base;