Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on arc.
[ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
[ paulmck: Apply feedback from Naresh Kamboju. ]
[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Apply feedback from Vineet Gupta. ]
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Cc: <linux-snps-arc@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vineet Gupta <vgupta@xxxxxxxxxx>
---
arch/arc/Kconfig | 1 +
arch/arc/include/asm/cmpxchg.h | 6 ++++--
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index fd0b0a0d4686a..163608fd49d18 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -13,6 +13,7 @@ config ARC
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
+ select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select ARCH_32BIT_OFF_T
select BUILDTIME_TABLE_SORT
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index e138fde067dea..58045c8983404 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -8,6 +8,7 @@
#include <linux/build_bug.h>
#include <linux/types.h>
+#include <linux/cmpxchg-emu.h>
#include <asm/barrier.h>
#include <asm/smp.h>
@@ -46,6 +47,9 @@
__typeof__(*(ptr)) _prev_; \
\
switch(sizeof((_p_))) { \
+ case 1: \
+ _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)_p_, (uintptr_t)_o_, (uintptr_t)_n_); \
+ break; \
case 4: \
_prev_ = __cmpxchg(_p_, _o_, _n_); \
break; \
@@ -65,8 +69,6 @@
__typeof__(*(ptr)) _prev_; \
unsigned long __flags; \
\
- BUILD_BUG_ON(sizeof(_p_) != 4); \
- \
/* \
* spin lock/unlock provide the needed smp_mb() before/after \
*/ \
--
2.40.1
