[PATCH v2 31/49] resources: Split out __allocate_resource()

Yinghai Lu
2015-07-14T22:53:01Z

It will not hold lock, so we could use it in other functions that
hold the resource lock already.

-v2: according to Linus, using "bool lock" as parameter
aka "conditionally take lock" is *wrong*.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/resource.c | 70 +++++++++++++++++++++++++++++++++++++++----------------
1 file changed, 50 insertions(+), 20 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 90552aa..830cc11 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -619,7 +619,7 @@ static int find_resource(struct resource *root, struct resource *new,
}

/**
- * reallocate_resource - allocate a slot in the resource tree given range & alignment.
+ * __reallocate_resource - allocate a slot in the resource tree given range & alignment.
* The resource will be relocated if the new size cannot be reallocated in the
* current location.
*
@@ -628,7 +628,7 @@ static int find_resource(struct resource *root, struct resource *new,
* @newsize: new size of the resource descriptor
* @constraint: the size and alignment constraints to be met.
*/
-static int reallocate_resource(struct resource *root, struct resource *old,
+static int __reallocate_resource(struct resource *root, struct resource *old,
resource_size_t newsize,
struct resource_constraint *constraint)
{
@@ -636,8 +636,6 @@ static int reallocate_resource(struct resource *root, struct resource *old,
struct resource new = *old;
struct resource *conflict;

- write_lock(&resource_lock);
-
if ((err = __find_resource(root, old, &new, newsize, constraint)))
goto out;

@@ -662,14 +660,13 @@ static int reallocate_resource(struct resource *root, struct resource *old,
BUG_ON(conflict);
}
out:
- write_unlock(&resource_lock);
return err;
}

-
/**
- * allocate_resource - allocate empty slot in the resource tree given range & alignment.
- * The resource will be reallocated with a new size if it was already allocated
+ * __allocate_resource - allocate empty slot in the resource tree given range & alignment.
+ * The resource will be reallocated with a new size if it was already
+ * allocated
* @root: root resource descriptor
* @new: resource descriptor desired by caller
* @size: requested resource region size
@@ -678,15 +675,17 @@ out:
* @align: alignment requested, in bytes
* @alignf: alignment function, optional, called if not NULL
* @alignf_data: arbitrary data to pass to the @alignf function
+ *
+ * Caller need to hold resource_lock if needed.
*/
-int allocate_resource(struct resource *root, struct resource *new,
- resource_size_t size, resource_size_t min,
- resource_size_t max, resource_size_t align,
- resource_size_t (*alignf)(void *,
- const struct resource *,
- resource_size_t,
- resource_size_t),
- void *alignf_data)
+static int __allocate_resource(struct resource *root, struct resource *new,
+ resource_size_t size, resource_size_t min,
+ resource_size_t max, resource_size_t align,
+ resource_size_t (*alignf)(void *,
+ const struct resource *,
+ resource_size_t,
+ resource_size_t),
+ void *alignf_data)
{
int err;
struct resource_constraint constraint;
@@ -700,20 +699,51 @@ int allocate_resource(struct resource *root, struct resource *new,
constraint.alignf = alignf;
constraint.alignf_data = alignf_data;

- if ( new->parent ) {
+ if (new->parent) {
/* resource is already allocated, try reallocating with
the new constraints */
- return reallocate_resource(root, new, size, &constraint);
+ return __reallocate_resource(root, new, size, &constraint);
}

- write_lock(&resource_lock);
err = find_resource(root, new, size, &constraint);
if (err >= 0 && __request_resource(root, new))
err = -EBUSY;
- write_unlock(&resource_lock);
+
return err;
}

+/**
+ * allocate_resource - allocate empty slot in the resource tree given range & alignment.
+ * The resource will be reallocated with a new size if it was already
+ * allocated
+ * @root: root resource descriptor
+ * @new: resource descriptor desired by caller
+ * @size: requested resource region size
+ * @min: minimum boundary to allocate
+ * @max: maximum boundary to allocate
+ * @align: alignment requested, in bytes
+ * @alignf: alignment function, optional, called if not NULL
+ * @alignf_data: arbitrary data to pass to the @alignf function
+ */
+int allocate_resource(struct resource *root, struct resource *new,
+ resource_size_t size, resource_size_t min,
+ resource_size_t max, resource_size_t align,
+ resource_size_t (*alignf)(void *,
+ const struct resource *,
+ resource_size_t,
+ resource_size_t),
+ void *alignf_data)
+{
+ int ret;
+
+ write_lock(&resource_lock);
+ ret = __allocate_resource(root, new, size, min, max, align,
+ alignf, alignf_data);
+ write_unlock(&resource_lock);
+
+ return ret;
+}
+
EXPORT_SYMBOL(allocate_resource);

/**
--
1.8.4.5