[PATCH cmpxchg 08/14] parisc: add u16 support to cmpxchg()

Paul E. McKenney
2024-04-08T17:49:47Z

From: Al Viro <viro@zeniv.linux.org.uk>

Add (and export) __cmpxchg_u16(), teach __cmpxchg() to use it.

And get rid of manual truncation down to u8, etc. in there - the
only reason for those is to avoid bogus warnings about constant
truncation from sparse, and those are easy to avoid by turning
that switch into conditional expression.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
arch/parisc/include/asm/cmpxchg.h | 19 +++++++++----------
arch/parisc/kernel/parisc_ksyms.c | 1 +
arch/parisc/lib/bitops.c | 1 +
3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/parisc/include/asm/cmpxchg.h b/arch/parisc/include/asm/cmpxchg.h
index 0924ebc576d28..bf0a0f1189eb2 100644
--- a/arch/parisc/include/asm/cmpxchg.h
+++ b/arch/parisc/include/asm/cmpxchg.h
@@ -56,25 +56,24 @@ __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
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new_, int size)
{
- switch (size) {
+ return
#ifdef CONFIG_64BIT
- case 8: return __cmpxchg_u64((u64 *)ptr, old, new_);
+ size == 8 ? __cmpxchg_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);
- }
- __cmpxchg_called_with_bad_pointer();
- return old;
+ size == 4 ? __cmpxchg_u32(ptr, old, new_) :
+ size == 2 ? __cmpxchg_u16(ptr, old, new_) :
+ size == 1 ? __cmpxchg_u8(ptr, old, new_) :
+ (__cmpxchg_called_with_bad_pointer(), old);
}

#define arch_cmpxchg(ptr, o, n) \
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index dcf61cbd31470..c1587aa35beb6 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 cae30a3eb6d9b..9df8100506427 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)
--
2.40.1