From: Atish Patra <atish.patra@wdc.com>
Date: Thu, 22 Aug 2019 07:51:49 +0000 (-0700)
Subject: RISC-V: Do not invoke SBI call if cpumask is empty
X-Git-Tag: v5.5-rc1~132^2~2^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6384423f49c804dbca02add1945e0ccf922cb522;p=thirdparty%2Fkernel%2Flinux.git

RISC-V: Do not invoke SBI call if cpumask is empty

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
---

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 24cd33d2c48f3..9ecaf73cd0515 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);
 }