From: Christoph Hellwig <hch@lst.de>
To: "Darrick J . Wong" <darrick.wong@oracle.com>
Cc: Damien Le Moal <Damien.LeMoal@wdc.com>,
Andreas Gruenbacher <agruenba@redhat.com>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 01/12] list.h: add a list_pop helper
Date: Mon, 24 Jun 2019 07:52:42 +0200 [thread overview]
Message-ID: <20190624055253.31183-2-hch@lst.de> (raw)
In-Reply-To: <20190624055253.31183-1-hch@lst.de>
We have a very common pattern where we want to delete the first entry
from a list and return it as the properly typed container structure.
Add a list_pop helper to implement this behavior.
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
include/linux/list.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/include/linux/list.h b/include/linux/list.h
index e951228db4b2..e07a5f54cc9d 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -500,6 +500,28 @@ static inline void list_splice_tail_init(struct list_head *list,
pos__ != head__ ? list_entry(pos__, type, member) : NULL; \
})
+/**
+ * list_pop - delete the first entry from a list and return it
+ * @list: the list to take the element from.
+ * @type: the type of the struct this is embedded in.
+ * @member: the name of the list_head within the struct.
+ *
+ * Note that if the list is empty, it returns NULL.
+ */
+#define list_pop(list, type, member) \
+({ \
+ struct list_head *head__ = (list); \
+ struct list_head *pos__ = READ_ONCE(head__->next); \
+ type *entry__ = NULL; \
+ \
+ if (pos__ != head__) { \
+ entry__ = list_entry(pos__, type, member); \
+ list_del(pos__); \
+ } \
+ \
+ entry__; \
+})
+
/**
* list_next_entry - get the next element in list
* @pos: the type * to cursor
--
2.20.1
next prev parent reply other threads:[~2019-06-24 5:53 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 5:52 lift the xfs writepage code into iomap Christoph Hellwig
2019-06-24 5:52 ` Christoph Hellwig [this message]
2019-06-24 14:53 ` [PATCH 01/12] list.h: add a list_pop helper Darrick J. Wong
2019-06-24 15:51 ` Matthew Wilcox
2019-06-25 10:06 ` Christoph Hellwig
2019-06-24 5:52 ` [PATCH 02/12] xfs: simplify xfs_chain_bio Christoph Hellwig
2019-06-24 15:14 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 03/12] xfs: fix a comment typo in xfs_submit_ioend Christoph Hellwig
2019-06-24 14:53 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 04/12] xfs: initialize ioma->flags in xfs_bmbt_to_iomap Christoph Hellwig
2019-06-24 14:57 ` Darrick J. Wong
2019-06-25 10:07 ` Christoph Hellwig
2019-06-25 15:13 ` Darrick J. Wong
2019-06-25 15:21 ` Christoph Hellwig
2019-06-24 5:52 ` [PATCH 05/12] xfs: use a struct iomap in xfs_writepage_ctx Christoph Hellwig
2019-06-24 15:50 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 06/12] xfs: remove XFS_TRANS_NOFS Christoph Hellwig
2019-06-24 15:58 ` Darrick J. Wong
2019-06-24 22:59 ` Dave Chinner
2019-06-25 10:12 ` Christoph Hellwig
2019-06-24 5:52 ` [PATCH 07/12] xfs: don't preallocate a transaction for file size updates Christoph Hellwig
2019-06-24 16:17 ` Darrick J. Wong
2019-06-24 23:15 ` Dave Chinner
2019-06-25 10:25 ` Christoph Hellwig
2019-06-27 22:23 ` Dave Chinner
2019-06-24 5:52 ` [PATCH 08/12] xfs: simplify xfs_ioend_can_merge Christoph Hellwig
2019-06-24 16:00 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 09/12] xfs: refactor the ioend merging code Christoph Hellwig
2019-06-24 16:04 ` Darrick J. Wong
2019-06-24 16:06 ` Nikolay Borisov
2019-06-25 10:14 ` Christoph Hellwig
2019-06-25 12:42 ` Nikolay Borisov
2019-06-25 14:45 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 10/12] xfs: remove the fork fields in the writepage_ctx and ioend Christoph Hellwig
2019-06-24 16:08 ` Darrick J. Wong
2019-06-24 5:52 ` [PATCH 11/12] iomap: move the xfs writeback code to iomap.c Christoph Hellwig
2019-06-24 15:46 ` Darrick J. Wong
2019-06-25 10:08 ` Christoph Hellwig
2019-06-24 23:43 ` Dave Chinner
2019-06-25 10:10 ` Christoph Hellwig
2019-06-28 0:45 ` Dave Chinner
2019-06-28 5:33 ` Christoph Hellwig
2019-07-01 0:08 ` Dave Chinner
2019-07-01 6:43 ` Christoph Hellwig
2019-07-01 23:09 ` Dave Chinner
2019-06-28 22:27 ` Luis Chamberlain
2019-07-11 21:31 ` Brendan Higgins
2019-06-24 5:52 ` [PATCH 12/12] iomap: add tracing for the address space operations Christoph Hellwig
2019-06-24 23:49 ` Dave Chinner
2019-06-25 10:15 ` Christoph Hellwig
2019-06-25 14:47 ` Darrick J. Wong
2019-06-27 22:35 ` Dave Chinner
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