Mar 13 2015

Staging: gdm72xx: Iterate list using list_for_each_entry 

Author: Somya Anand <somyaanand214@gmail.com>

Code using doubly linked list is iterated generally  using list_empty and
list_entry functions, but it can be better written using list_for_each_entry
macro.

This patch replaces the while loop containing list_empty and list_entry with
list_for_each_entry and list_for_each_entry_safe. list_for_each_entry is a
macro which is used to iterate over a list of given type. So while loop used to
iterate over a list can be replaced with list_for_each_entry macro. However, if
list_del is used in the loop, then list_for_each_entry_safe is a better choice.
This transformation is done by using the following coccinelle script.

@ rule1 @
expression E1;
identifier I1, I2;
type T;
iterator name list_for_each_entry;
@@

- while (list_empty(&E1) == 0)
+ list_for_each_entry (I1, &E1, I2)
 {
	...when != T *I1;
- 	I1 = list_entry(E1.next, T, I2);
    ...when != list_del(...);
       when != list_del_init(...);
 }

@ rule2  @
expression E1;
identifier I1, I2;
type T;
iterator name list_for_each_entry_safe;
@@
   T *I1;
+  T *tmp;
  ...
- while (list_empty(&E1) == 0)
+ list_for_each_entry_safe (I1, tmp, &E1, I2)
 {
	...when != T *I1;
- 	I1 = list_entry(E1.next, T, I2);
    ...
 }

Signed-off-by: Somya Anand 
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/staging/gdm72xx/gdm_wimax.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
 
diff --git a/drivers/staging/gdm72xx/gdm_wimax.c b/drivers/staging/gdm72xx/gdm_wimax.c
index 9cab54b..32fe93b 100644
--- a/drivers/staging/gdm72xx/gdm_wimax.c
+++ b/drivers/staging/gdm72xx/gdm_wimax.c
@@ -129,11 +129,11 @@ static void __gdm_wimax_event_send(struct work_struct *work)
 	int idx;
 	unsigned long flags;
 	struct evt_entry *e;
+	struct evt_entry *tmp;
 
 	spin_lock_irqsave(&wm_event.evt_lock, flags);
 
-	while (!list_empty(&wm_event.evtq)) {
-		e = list_entry(wm_event.evtq.next, struct evt_entry, list);
+	list_for_each_entry_safe(e, tmp, &wm_event.evtq, list) {
 		spin_unlock_irqrestore(&wm_event.evt_lock, flags);
 
 		if (sscanf(e->dev->name, "wm%d", &idx) == 1)

qlambert