From d28d86a07dbca4b6e33032196ef4a9a7121181b4 Mon Sep 17 00:00:00 2001
From: Heiko Carstens <hca@linux.ibm.com>
Date: Fri, 17 Mar 2023 14:51:41 +0100
Subject: [PATCH] s390/mm: make use of atomic_fetch_xor()
Make use of atomic_fetch_xor() instead of an atomic_cmpxchg() loop to
implement atomic_xor_bits() (aka atomic_xor_return()). This makes the C
code more readable and in addition generates better code, since for z196
and newer a single lax instruction is generated instead of a cmpxchg()
loop.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/mm/pgalloc.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index 0f68b7257e08d..66ab68db98428 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -133,13 +133,7 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
{
- unsigned int old, new;
-
- do {
- old = atomic_read(v);
- new = old ^ bits;
- } while (atomic_cmpxchg(v, old, new) != old);
- return new;
+ return atomic_fetch_xor(bits, v) ^ bits;
}
#ifdef CONFIG_PGSTE
--
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