md: use list_for_each_entry macro directly

The rdev_for_each macro defined in <linux/raid/md_k.h> is identical to
list_for_each_entry_safe, from <linux/list.h>, it should be defined to
use list_for_each_entry_safe, instead of reinventing the wheel.

But some calls to each_entry_safe don't really need a safe version,
just a direct list_for_each_entry is enough, this could save a temp
variable (tmp) in every function that used rdev_for_each.

In this patch, most rdev_for_each loops are replaced by list_for_each_entry,
totally save many tmp vars; and only in the other situations that will call
list_del to delete an entry, the safe version is used.

Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 4 insertions, 7 deletions

diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 663803eaf0de..8f9a54c1fb0e 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -335,17 +335,14 @@ static inline char * mdname (mddev_t * mddev)
  * iterates through some rdev ringlist. It's safe to remove the
  * current 'rdev'. Dont touch 'tmp' though.
  */
-#define rdev_for_each_list(rdev, tmp, list)                             \
-                                                                        \
-        for ((tmp) = (list).next;                                       \
-                (rdev) = (list_entry((tmp), mdk_rdev_t, same_set)),     \
-                        (tmp) = (tmp)->next, (tmp)->prev != &(list)     \
-                ; )
+#define rdev_for_each_list(rdev, tmp, head)                             \
+        list_for_each_entry_safe(rdev, tmp, head, same_set)
+
 /*
  * iterates through the 'same array disks' ringlist
  */
 #define rdev_for_each(rdev, tmp, mddev)                         \
-        rdev_for_each_list(rdev, tmp, (mddev)->disks)
+        list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
 
 #define rdev_for_each_rcu(rdev, mddev)                          \
         list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)