[PATCH 3/3] mm: Fix bugs in region_is_ram()

Toshi Kani
2015-06-19T21:45:08Z

region_is_ram(), which looks up the resource to check if
a target range is RAM, always returns -1 due to a bug in
the range check. It always breaks the loop at the first
entry of the resouce table.

The function compares p->flags and flags, which also has
a bug. The flags is declared as int, which makes it as
a negative value with IORESOURCE_BUSY (0x80000000) set
while p->flags is unsigned long.

Fix the range check and flags so that region_is_ram()
works as advertised.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
kernel/resource.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 90552aa..fed052a 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -504,13 +504,13 @@ int region_is_ram(resource_size_t start, unsigned long size)
{
struct resource *p;
resource_size_t end = start + size - 1;
- int flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
const char *name = "System RAM";
int ret = -1;

read_lock(&resource_lock);
for (p = iomem_resource.child; p ; p = p->sibling) {
- if (end < p->start)
+ if (p->end < start)
continue;

if (p->start <= start && end <= p->end) {
@@ -521,7 +521,7 @@ int region_is_ram(resource_size_t start, unsigned long size)
ret = 1;
break;
}
- if (p->end < start)
+ if (end < p->start)
break; /* not found */
}
read_unlock(&resource_lock);