linux-kernel - [PATCH] sort.h: hoist cmp_int() into generic header file

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Message-ID: <20250427201451.900730-1-pchelkin@ispras.ru>
Date: Sun, 27 Apr 2025 23:14:49 +0300
From: Fedor Pchelkin <pchelkin@...ras.ru>
To: linux-kernel@...r.kernel.org
Cc: Fedor Pchelkin <pchelkin@...ras.ru>,
	Coly Li <colyli@...nel.org>,
	Kent Overstreet <kent.overstreet@...ux.dev>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	Carlos Maiolino <cem@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Darrick J. Wong" <djwong@...nel.org>,
	linux-bcache@...r.kernel.org,
	linux-bcachefs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	lvc-project@...uxtesting.org
Subject: [PATCH] sort.h: hoist cmp_int() into generic header file

Deduplicate the same functionality implemented in several places by
moving the cmp_int() helper macro into linux/sort.h.

The macro performs a three-way comparison of the arguments mostly useful
in different sorting strategies and algorithms.

Suggested-by: Darrick J. Wong <djwong@...nel.org>
Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>
---

https://lore.kernel.org/linux-xfs/20250426150359.GQ25675@frogsfrogsfrogs/T/#u

 drivers/md/bcache/btree.c |  3 +--
 fs/bcachefs/util.h        |  3 +--
 fs/pipe.c                 |  3 +--
 fs/xfs/xfs_zone_gc.c      |  2 --
 include/linux/sort.h      | 10 ++++++++++
 5 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index ed40d8600656..2cc2eb24dc8a 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -36,6 +36,7 @@
 #include <linux/sched/clock.h>
 #include <linux/rculist.h>
 #include <linux/delay.h>
+#include <linux/sort.h>
 #include <trace/events/bcache.h>
 
 /*
@@ -559,8 +560,6 @@ static void mca_data_alloc(struct btree *b, struct bkey *k, gfp_t gfp)
 	}
 }
 
-#define cmp_int(l, r)		((l > r) - (l < r))
-
 #ifdef CONFIG_PROVE_LOCKING
 static int btree_lock_cmp_fn(const struct lockdep_map *_a,
 			     const struct lockdep_map *_b)
diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
index 3e52c7f8ddd2..7ec1fc8b46f9 100644
--- a/fs/bcachefs/util.h
+++ b/fs/bcachefs/util.h
@@ -16,6 +16,7 @@
 #include <linux/preempt.h>
 #include <linux/ratelimit.h>
 #include <linux/slab.h>
+#include <linux/sort.h>
 #include <linux/vmalloc.h>
 #include <linux/workqueue.h>
 
@@ -669,8 +670,6 @@ static inline void percpu_memset(void __percpu *p, int c, size_t bytes)
 
 u64 *bch2_acc_percpu_u64s(u64 __percpu *, unsigned);
 
-#define cmp_int(l, r)		((l > r) - (l < r))
-
 static inline int u8_cmp(u8 l, u8 r)
 {
 	return cmp_int(l, r);
diff --git a/fs/pipe.c b/fs/pipe.c
index da45edd68c41..45077c37bad1 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -26,6 +26,7 @@
 #include <linux/memcontrol.h>
 #include <linux/watch_queue.h>
 #include <linux/sysctl.h>
+#include <linux/sort.h>
 
 #include <linux/uaccess.h>
 #include <asm/ioctls.h>
@@ -76,8 +77,6 @@ static unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
  * -- Manfred Spraul <manfred@...orfullife.com> 2002-05-09
  */
 
-#define cmp_int(l, r)		((l > r) - (l < r))
-
 #ifdef CONFIG_PROVE_LOCKING
 static int pipe_lock_cmp_fn(const struct lockdep_map *a,
 			    const struct lockdep_map *b)
diff --git a/fs/xfs/xfs_zone_gc.c b/fs/xfs/xfs_zone_gc.c
index 81c94dd1d596..2f9caa3eb828 100644
--- a/fs/xfs/xfs_zone_gc.c
+++ b/fs/xfs/xfs_zone_gc.c
@@ -290,8 +290,6 @@ xfs_zone_gc_query_cb(
 	return 0;
 }
 
-#define cmp_int(l, r)		((l > r) - (l < r))
-
 static int
 xfs_zone_gc_rmap_rec_cmp(
 	const void			*a,
diff --git a/include/linux/sort.h b/include/linux/sort.h
index 8e5603b10941..c01ef804a0eb 100644
--- a/include/linux/sort.h
+++ b/include/linux/sort.h
@@ -4,6 +4,16 @@
 
 #include <linux/types.h>
 
+/**
+ * cmp_int - perform a three-way comparison of the arguments
+ * @l: the left argument
+ * @r: the right argument
+ *
+ * Return: 1 if the left argument is greater than the right one; 0 if the
+ * arguments are equal; -1 if the left argument is less than the right one.
+ */
+#define cmp_int(l, r) (((l) > (r)) - ((l) < (r)))
+
 void sort_r(void *base, size_t num, size_t size,
 	    cmp_r_func_t cmp_func,
 	    swap_r_func_t swap_func,
-- 
2.49.0