[PATCH v3 3/3] RISC-V: Do not invoke SBI call if cpumask is empty

[Atish Patra]

SBI calls are expensive. If cpumask is empty, there is no need to
trap via SBI as no remote tlb flushing is required.

Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
---
 arch/riscv/mm/tlbflush.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 9f58b3790baa..2bd3c418d769 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -21,6 +21,9 @@ static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
 		goto issue_sfence;
 	}
 
+	if (cpumask_empty(cmask))
+		goto done;
+
 	if (cpumask_test_cpu(cpuid, cmask) && cpumask_weight(cmask) == 1) {
 		if (size <= PAGE_SIZE && size != -1)
 			local_flush_tlb_page(start);
-- 
2.21.0