[PATCH v4 1/3] RISC-V: Do not invoke SBI call if cpumask is empty

Atish Patra
2019-08-22T07:59:01Z

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@wdc.com>
---
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 df93b26f1b9d..1293b8017ee0 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -14,6 +14,9 @@ static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
{
struct cpumask hmask;

+ if (cpumask_empty(cmask))
+ return;
+
riscv_cpuid_to_hartid_mask(cmask, &hmask);
sbi_remote_sfence_vma(hmask.bits, start, size);
}
--
2.21.0