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ARC: Emulate one-byte cmpxchg

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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@kernel.org>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: <linux-snps-arc@lists.infradead.org>
Acked-by: Vineet Gupta <vgupta@kernel.org>
This commit is contained in:
Paul E. McKenney 2024-03-18 01:27:35 -07:00
parent 8400291e28
commit f2519d4d4f
2 changed files with 5 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arc/Kconfig
View File

@ -13,6 +13,7 @@ config ARC
select ARCH_HAS_SETUP_DMA_OPS select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SYNC_DMA_FOR_CPU select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_HAS_SYNC_DMA_FOR_DEVICE
select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select ARCH_32BIT_OFF_T select ARCH_32BIT_OFF_T
select BUILDTIME_TABLE_SORT select BUILDTIME_TABLE_SORT

6
arch/arc/include/asm/cmpxchg.h
View File

@ -8,6 +8,7 @@
#include <linux/build_bug.h> #include <linux/build_bug.h>
#include <linux/types.h> #include <linux/types.h>
#include <linux/cmpxchg-emu.h>
#include <asm/barrier.h> #include <asm/barrier.h>
#include <asm/smp.h> #include <asm/smp.h>
@ -46,6 +47,9 @@
__typeof__(*(ptr)) _prev_; \ __typeof__(*(ptr)) _prev_; \
\ \
switch(sizeof((_p_))) { \ switch(sizeof((_p_))) { \
case 1: \
_prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *)_p_, (uintptr_t)_o_, (uintptr_t)_n_); \
break; \
case 4: \ case 4: \
_prev_ = __cmpxchg(_p_, _o_, _n_); \ _prev_ = __cmpxchg(_p_, _o_, _n_); \
break; \ break; \
@ -65,8 +69,6 @@
__typeof__(*(ptr)) _prev_; \ __typeof__(*(ptr)) _prev_; \
unsigned long __flags; \ unsigned long __flags; \
\ \
BUILD_BUG_ON(sizeof(_p_) != 4); \
\
/* \ /* \
* spin lock/unlock provide the needed smp_mb() before/after \ * spin lock/unlock provide the needed smp_mb() before/after \
*/ \ */ \