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Subject[PATCH 1/3 v2] resource: fix an error which walks through iomem resources
When we walk through iomem resources by calling walk_iomem_res_desc(),
the values of the function parameter may be modified in the while loop
of __walk_iomem_res_desc(), which will cause us to not get the desired
result in some cases.

At present, it only restores the original value of res->end, but it
doesn't restore the original value of res->flags in the while loop of
__walk_iomem _res_desc(). Whenever the find_next_iomem_res() finds a
resource and returns the result, the original values of this resource
will be modified, which might lead to an error in the next loop. For

The original value of resource flags is:
res->flags=0x80000200(initial value)

p->flags _ 0x81000200 _ _ 0x80000200 _
/ \ / \
0 0xffffffff
(memory address ranges)

Note: if ((p->flags & res->flags) != res->flags) continue;

When the resource A is found, the original value of this resource flags
will be changed to 0x81000200(res->flags=0x81000200), and continue to
look for the next resource, when the loop reaches resource B, it can not
get the resource B any more(you can refer to the for loop of find_next
_iomem_res()), because the value of conditional expression will become
true and will also jump the resource B.

In fact, we should get the resource A and B when we walk through the
whole tree, but it only gets the resource A, the resource B is missed.

Signed-off-by: Dave Young <>
Signed-off-by: Lianbo Jiang <>
kernel/resource.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/resource.c b/kernel/resource.c
index 30e1bc68503b..f5d9fc70a04c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -375,6 +375,7 @@ static int __walk_iomem_res_desc(struct resource *res, unsigned long desc,
int (*func)(struct resource *, void *))
u64 orig_end = res->end;
+ u64 orig_flags = res->flags;
int ret = -1;

while ((res->start < res->end) &&
@@ -385,6 +386,7 @@ static int __walk_iomem_res_desc(struct resource *res, unsigned long desc,

res->start = res->end + 1;
res->end = orig_end;
+ res->flags = orig_flags;

return ret;
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