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Message-ID: <20130605020341.GA27240@logfs.org>
Date: Tue, 4 Jun 2013 22:03:41 -0400
From: Jörn Engel <joern@...fs.org>
To: Arne Jansen <sensille@....net>
Cc: Chris Mason <clmason@...ionio.com>,
Christoph Hellwig <hch@...radead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>
Subject: [PATCH 1/2] list: add while_list_drain_entry
I have seen a lot of boilerplate code that either follows the pattern of
while (!list_empty(head)) {
pos = list_entry(head->next, struct foo, list);
list_del(pos->list);
...
}
or some variant thereof.
With this patch in, people can use
while_list_drain_entry(pos, head, list) {
...
}
The patch also adds a while_list_drain variant, even though I have
only found a single user for that one so far.
Signed-off-by: Joern Engel <joern@...fs.org>
---
include/linux/list.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/list.h b/include/linux/list.h
index 6a1f8df..ab39c7d 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -557,6 +557,24 @@ static inline void list_splice_tail_init(struct list_head *list,
#define list_safe_reset_next(pos, n, member) \
n = list_entry(pos->member.next, typeof(*pos), member)
+/**
+ * while_list_drain - removes an entry from the list until it is empty
+ * @pos: the &struct list_head to use as a loop cursor.
+ * @head: the head of your list.
+ */
+#define while_list_drain(pos, head) \
+ while (list_empty(head) ? 0 : (pos = (head)->next, list_del(pos), 1))
+
+/**
+ * while_list_drain_entry - removes an entry from the list until it is empty
+ * @pos: the type * to use as loop cursor.
+ * @head: the head of your list.
+ * @member: the name of the list_struct within the struct
+ */
+#define while_list_drain_entry(pos, head, member) \
+ while (list_empty(head) && (pos = list_first_entry((head), \
+ typeof(*pos), member), list_del((head)->next), 1))
+
/*
* Double linked lists with a single pointer list head.
* Mostly useful for hash tables where the two pointer list head is
--
1.7.10.4
--
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