[PATCH v2 1/4] resource: Change __request_region to inherit from immediate parent

Toshi Kani
2016-03-02T21:59:33Z

__request_region() sets 'flags' of a new resource from @parent
as it inherits the parent's attribute. When a target resource
has a conflict, this function inserts the new resource entry
under the conflicted entry by updating @parent. In this case,
the new resource entry needs to inherit attribute from the updated
parent. This conflict is a typical case since __request_region()
is used to allocate a new resource from a specific resource range.

For instance, request_mem_region() calls __request_region() with
@parent set to &iomem_resource, which is the root entry of the
whole iomem range. When this request results in inserting a new
entry "DEV-A" under "BUS-1", "DEV-A" needs to inherit from the
immediate parent "BUS-1" as it holds specific attribute for the
range.

root (&iomem_resource)
:
+ "BUS-1"
+ "DEV-A"

Change __request_region() to set 'flags' and 'desc' of a new entry
from the immediate parent.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
---
kernel/resource.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 4d46605..5a56e8f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1085,15 +1085,16 @@ struct resource * __request_region(struct resource *parent,
res->name = name;
res->start = start;
res->end = start + n - 1;
- res->flags = resource_type(parent) | resource_ext_type(parent);
- res->flags |= IORESOURCE_BUSY | flags;
- res->desc = IORES_DESC_NONE;

write_lock(&resource_lock);

for (;;) {
struct resource *conflict;

+ res->flags = resource_type(parent) | resource_ext_type(parent);
+ res->flags |= IORESOURCE_BUSY | flags;
+ res->desc = parent->desc;
+
conflict = __request_resource(parent, res);
if (!conflict)
break;