linux-kernel - [PATCH 8/8] parisc: add u16 support to cmpxchg()

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Message-Id: <20240402042835.11815-8-viro@zeniv.linux.org.uk>
Date: Tue,  2 Apr 2024 00:28:35 -0400
From: Al Viro <viro@...iv.linux.org.uk>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	kernel-team@...a.com,
	"David S. Miller" <davem@...emloft.net>,
	Andreas Larsson <andreas@...sler.com>,
	Palmer Dabbelt <palmer@...osinc.com>,
	Arnd Bergmann <arnd@...db.de>,
	Marco Elver <elver@...gle.com>
Subject: [PATCH 8/8] parisc: add u16 support to cmpxchg()

Add (and export) __cmpxchg_u16(), teach __cmpxchg() to use it.
And get rid of the casts of {old,new_} in __cmpxchg() - __cmpxchg_u...()
has those arguments declared as u<size> and conversion from unsigned
long to those is automatic.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 arch/parisc/include/asm/cmpxchg.h | 13 +++++++------
 arch/parisc/kernel/parisc_ksyms.c |  1 +
 arch/parisc/lib/bitops.c          |  1 +
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/parisc/include/asm/cmpxchg.h b/arch/parisc/include/asm/cmpxchg.h
index 0924ebc576d2..1a0eec8c91f5 100644
--- a/arch/parisc/include/asm/cmpxchg.h
+++ b/arch/parisc/include/asm/cmpxchg.h
@@ -56,10 +56,11 @@ __arch_xchg(unsigned long x, volatile void *ptr, int size)
 /* bug catcher for when unsupported size is used - won't link */
 extern void __cmpxchg_called_with_bad_pointer(void);
 
-/* __cmpxchg_u32/u64 defined in arch/parisc/lib/bitops.c */
+/* __cmpxchg_u... defined in arch/parisc/lib/bitops.c */
+extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);
+extern u16 __cmpxchg_u16(volatile u16 *ptr, u16 old, u16 new_);
 extern u32 __cmpxchg_u32(volatile u32 *m, u32 old, u32 new_);
 extern u64 __cmpxchg_u64(volatile u64 *ptr, u64 old, u64 new_);
-extern u8 __cmpxchg_u8(volatile u8 *ptr, u8 old, u8 new_);
 
 /* don't worry...optimizer will get rid of most of this */
 static inline unsigned long
@@ -67,11 +68,11 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
 {
 	switch (size) {
 #ifdef CONFIG_64BIT
-	case 8: return __cmpxchg_u64((u64 *)ptr, old, new_);
+	case 8: return __cmpxchg_u64((volatile u64 *)ptr, old, new_);
 #endif
-	case 4: return __cmpxchg_u32((unsigned int *)ptr,
-				     (unsigned int)old, (unsigned int)new_);
-	case 1: return __cmpxchg_u8((u8 *)ptr, old & 0xff, new_ & 0xff);
+	case 4: return __cmpxchg_u32((volatile u32 *)ptr, old, new_);
+	case 2: return __cmpxchg_u16((volatile u16 *)ptr, old, new_);
+	case 1: return __cmpxchg_u8((volatile u8 *)ptr, old, new_);
 	}
 	__cmpxchg_called_with_bad_pointer();
 	return old;
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index dcf61cbd3147..c1587aa35beb 100644
--- a/arch/parisc/kernel/parisc_ksyms.c
+++ b/arch/parisc/kernel/parisc_ksyms.c
@@ -23,6 +23,7 @@ EXPORT_SYMBOL(memset);
 EXPORT_SYMBOL(__xchg8);
 EXPORT_SYMBOL(__xchg32);
 EXPORT_SYMBOL(__cmpxchg_u8);
+EXPORT_SYMBOL(__cmpxchg_u16);
 EXPORT_SYMBOL(__cmpxchg_u32);
 EXPORT_SYMBOL(__cmpxchg_u64);
 #ifdef CONFIG_SMP
diff --git a/arch/parisc/lib/bitops.c b/arch/parisc/lib/bitops.c
index cae30a3eb6d9..9df810050642 100644
--- a/arch/parisc/lib/bitops.c
+++ b/arch/parisc/lib/bitops.c
@@ -71,4 +71,5 @@ unsigned long notrace __xchg8(char x, volatile char *ptr)
 
 CMPXCHG(u64)
 CMPXCHG(u32)
+CMPXCHG(u16)
 CMPXCHG(u8)
-- 
2.39.2