[PATCH v3 RESEND 1/2] riscv: select ARCH_USE_CMPXCHG_LOCKREF

[Jisheng Zhang <jszhang@kernel.org>]

Select ARCH_USE_CMPXCHG_LOCKREF to enable the cmpxchg-based lockless
lockref implementation for riscv.

Using Linus' test case[1] on TH1520 platform, I see a 11.2% improvement.
On JH7110 platform, I see 12.0% improvement.

Link: http://marc.info/?l=linux-fsdevel&m=137782380714721&w=4 [1]
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index aba42b2bf660..7895c77545f1 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -58,6 +58,7 @@ config RISCV
 	select ARCH_SUPPORTS_PAGE_TABLE_CHECK if MMU
 	select ARCH_SUPPORTS_PER_VMA_LOCK if MMU
 	select ARCH_SUPPORTS_SHADOW_CALL_STACK if HAVE_SHADOW_CALL_STACK
+	select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
 	select ARCH_USE_MEMTEST
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USES_CFI_TRAPS if CFI_CLANG
-- 
2.43.0