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[Concept,11/12] linux: Add hash.h header with hash_64 function

Message ID 20260118133734.11.397d736c6788ee2e24a276a8634e9d22d18dd84d@changeid
State New
Headers
Series ext4l: Continue reducing ext4_uboot.h size with more headers |

Commit Message

Simon Glass Jan. 18, 2026, 8:37 p.m. UTC 
  From: Simon Glass <simon.glass@canonical.com>

Create linux/hash.h with hash_64() and hash_32() hash functions.

Update ext4_uboot.h to use the new header instead of duplicating the
hash_64 definition.

Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>

---

 fs/ext4l/ext4_uboot.h |  6 +++---
 include/linux/hash.h  | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 include/linux/hash.h
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Patch

diff --git a/fs/ext4l/ext4_uboot.h b/fs/ext4l/ext4_uboot.h
index 4bc25b73f76..b861079bf48 100644
--- a/fs/ext4l/ext4_uboot.h
+++ b/fs/ext4l/ext4_uboot.h
@@ -901,8 +901,8 @@  void mapping_clear_folio_cache(struct address_space *mapping);
 
 /* try_cmpxchg is now in asm-generic/atomic.h */
 
-/* hash_64 - simple 64-bit hash */
-#define hash_64(val, bits)	((unsigned long)((val) >> (64 - (bits))))
+/* hash_64 - use linux/hash.h */
+#include <linux/hash.h>
 
 /* Dentry operations are now in linux/dcache.h */
 #define finish_open_simple(f, e)		(e)
@@ -1820,7 +1820,7 @@  int ext4_update_overhead(struct super_block *sb, bool force);
 /* fsmap is now in linux/fsmap.h */
 #include <linux/fsmap.h>
 
-/* list_sort and sort stubs for fsmap.c */
+/* list_sort and sort stubs for fsmap.c - not used in U-Boot */
 #define list_sort(priv, head, cmp) \
 	do { (void)(priv); (void)(head); (void)(cmp); } while (0)
 #define sort(base, num, size, cmp, swap) \
diff --git a/include/linux/hash.h b/include/linux/hash.h
new file mode 100644
index 00000000000..276619ca310
--- /dev/null
+++ b/include/linux/hash.h
@@ -0,0 +1,33 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Hash functions for U-Boot
+ *
+ * Based on Linux hash.h - fast hashing routines.
+ */
+#ifndef _LINUX_HASH_H
+#define _LINUX_HASH_H
+
+#include <linux/types.h>
+
+/**
+ * hash_64() - 64-bit hash function
+ * @val: value to hash
+ * @bits: number of bits in result
+ *
+ * Simple hash by shifting. In Linux this uses multiplication by a
+ * golden ratio constant, but for U-Boot a simple shift suffices.
+ *
+ * Return: hash value with @bits significant bits
+ */
+#define hash_64(val, bits)	((unsigned long)((val) >> (64 - (bits))))
+
+/**
+ * hash_32() - 32-bit hash function
+ * @val: value to hash
+ * @bits: number of bits in result
+ *
+ * Return: hash value with @bits significant bits
+ */
+#define hash_32(val, bits)	((unsigned int)((val) >> (32 - (bits))))
+
+#endif /* _LINUX_HASH_H */