device-dax: Avoid an unnecessary check in alloc_dev_dax_range()

Swap the calling sequence of krealloc() and __request_region(), call the
latter first. In this way, the value of dev_dax->nr_range does not need to
be considered when __request_region() failed.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20201219081840.1149-2-thunder.leizhen@huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 720cd14..737b207 100644 (file)
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -772,22 +772,14 @@ static int alloc_dev_dax_range(struct dev_dax *dev_dax, u64 start,
                return 0;
        }
 
-       ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
-                       * (dev_dax->nr_range + 1), GFP_KERNEL);
-       if (!ranges)
+       alloc = __request_region(res, start, size, dev_name(dev), 0);
+       if (!alloc)
                return -ENOMEM;
 
-       alloc = __request_region(res, start, size, dev_name(dev), 0);
-       if (!alloc) {
-               /*
-                * If this was an empty set of ranges nothing else
-                * will release @ranges, so do it now.
-                */
-               if (!dev_dax->nr_range) {
-                       kfree(ranges);
-                       ranges = NULL;
-               }
-               dev_dax->ranges = ranges;
+       ranges = krealloc(dev_dax->ranges, sizeof(*ranges)
+                       * (dev_dax->nr_range + 1), GFP_KERNEL);
+       if (!ranges) {
+               __release_region(res, alloc->start, resource_size(alloc));
                return -ENOMEM;
        }