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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2015-07-27 18:04:00 +0300
committerLee Jones <lee.jones@linaro.org>2015-07-28 08:50:42 +0100
commit3d060aeb72113cda0acf906bfe26914fc689506a (patch)
tree683028071415f9724d618e8a4f84124a10111a6d /drivers/base/core.c
parent2e0fed7f7cdc41679e209c5636ad7537dc6210a9 (diff)
driver core: implement device_for_each_child_reverse()
The new function device_for_each_child_reverse() is helpful to traverse the registered devices in a reversed order, e.g. in the case when an operation on each device should be done first on the last added device, then on one before last and so on. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/base/core.c')
-rw-r--r--drivers/base/core.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index dafae6d2f7ac..7d6279554afc 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1252,6 +1252,19 @@ void device_unregister(struct device *dev)
}
EXPORT_SYMBOL_GPL(device_unregister);
+static struct device *prev_device(struct klist_iter *i)
+{
+ struct klist_node *n = klist_prev(i);
+ struct device *dev = NULL;
+ struct device_private *p;
+
+ if (n) {
+ p = to_device_private_parent(n);
+ dev = p->device;
+ }
+ return dev;
+}
+
static struct device *next_device(struct klist_iter *i)
{
struct klist_node *n = klist_next(i);
@@ -1341,6 +1354,36 @@ int device_for_each_child(struct device *parent, void *data,
EXPORT_SYMBOL_GPL(device_for_each_child);
/**
+ * device_for_each_child_reverse - device child iterator in reversed order.
+ * @parent: parent struct device.
+ * @fn: function to be called for each device.
+ * @data: data for the callback.
+ *
+ * Iterate over @parent's child devices, and call @fn for each,
+ * passing it @data.
+ *
+ * We check the return of @fn each time. If it returns anything
+ * other than 0, we break out and return that value.
+ */
+int device_for_each_child_reverse(struct device *parent, void *data,
+ int (*fn)(struct device *dev, void *data))
+{
+ struct klist_iter i;
+ struct device *child;
+ int error = 0;
+
+ if (!parent->p)
+ return 0;
+
+ klist_iter_init(&parent->p->klist_children, &i);
+ while ((child = prev_device(&i)) && !error)
+ error = fn(child, data);
+ klist_iter_exit(&i);
+ return error;
+}
+EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
+
+/**
* device_find_child - device iterator for locating a particular device.
* @parent: parent struct device
* @match: Callback function to check device

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