[PATCH] of/flattree: Fix crash when device tree absent

From: Grant Likely
Date: Fri Jun 25 2010 - 18:08:27 EST

This patch fixes the condition where device tree support is compiled
in, but no device tree was proved by firmware. It makes
of_platform_bus_probe() explicitly check for a NULL device tree
pointer, and adds an error message if the device tree was unable
to be flattened.

Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxxxx>
drivers/of/fdt.c | 2 ++
drivers/of/platform.c | 2 ++
2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index b6987bb..beda593 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -94,6 +94,8 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
} while (1);

+ if (rc)
+ pr_err("Failed to unflatten device tree blob. rc=%i\n", rc);
return rc;

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 3eb4cf6..1f5a210 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -640,6 +640,8 @@ int of_platform_bus_probe(struct device_node *root,
root = of_find_node_by_path("/");
+ if (root == NULL)
+ return -EINVAL;

pr_debug(" starting at: %s\n", root->full_name);

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