[POWERPC] Fix cell IOMMU null pointer explosion on old firmwares

The cell IOMMU fixed mapping support has a null pointer bug if you run
it on older firmwares that don't contain the "dma-ranges" properties.
Fix it and convert to using of_get_next_parent() while we're there.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index df330666ccc9cef8026f80d489ec13dc08c5feb1..a276064471b3a0a9449d6cdedc408073415d635c 100644 (file)
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -26,6 +26,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
+#include <linux/of.h>
 #include <linux/of_platform.h>
 
 #include <asm/prom.h>
@@ -789,18 +790,16 @@ static int __init cell_iommu_init_disabled(void)
 static u64 cell_iommu_get_fixed_address(struct device *dev)
 {
        u64 cpu_addr, size, best_size, pci_addr = OF_BAD_ADDR;
-       struct device_node *tmp, *np;
+       struct device_node *np;
        const u32 *ranges = NULL;
        int i, len, best;
 
-       np = dev->archdata.of_node;
-       of_node_get(np);
-       ranges = of_get_property(np, "dma-ranges", &len);
-       while (!ranges && np) {
-               tmp = of_get_parent(np);
-               of_node_put(np);
-               np = tmp;
+       np = of_node_get(dev->archdata.of_node);
+       while (np) {
                ranges = of_get_property(np, "dma-ranges", &len);
+               if (ranges)
+                       break;
+               np = of_get_next_parent(np);
        }
 
        if (!ranges) {