linux-kernel - [PATCH] KVM: x86: Optimize your code to avoid unnecessary calls

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Message-Id: <20221201014237.5764-1-liujing@cmss.chinamobile.com>
Date:   Wed, 30 Nov 2022 20:42:37 -0500
From:   liujing <liujing@...s.chinamobile.com>
To:     pbonzini@...hat.com
Cc:     tglx@...utronix.de, mingo@...hat.com, dave.hansen@...ux.intel.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        liujing <liujing@...s.chinamobile.com>
Subject: [PATCH] KVM: x86: Optimize your code to avoid unnecessary calls

In the kvm_vm_ioctl_get_irqchip function, we can removethe 
definition of the r variable instead of return 0 in the end.
In the kvm_vm_ioctl_set_irqchip function, also use return 0 instead,
return -EINVAL to avoid calling kvm_pic_update_irq again.

Signed-off-by: liujing <liujing@...s.chinamobile.com>
---
 arch/x86/kvm/x86.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2835bd796639..8e94f3d730ee 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6002,9 +6002,7 @@ static unsigned long kvm_vm_ioctl_get_nr_mmu_pages(struct kvm *kvm)
 static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 {
 	struct kvm_pic *pic = kvm->arch.vpic;
-	int r;
 
-	r = 0;
 	switch (chip->chip_id) {
 	case KVM_IRQCHIP_PIC_MASTER:
 		memcpy(&chip->chip.pic, &pic->pics[0],
@@ -6018,18 +6016,15 @@ static int kvm_vm_ioctl_get_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 		kvm_get_ioapic(kvm, &chip->chip.ioapic);
 		break;
 	default:
-		r = -EINVAL;
-		break;
+		return -EINVAL;
 	}
-	return r;
+	return 0;
 }
 
 static int kvm_vm_ioctl_set_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 {
 	struct kvm_pic *pic = kvm->arch.vpic;
-	int r;
-
-	r = 0;	
 	switch (chip->chip_id) {
 	case KVM_IRQCHIP_PIC_MASTER:
 		spin_lock(&pic->lock);
@@ -6047,11 +6042,10 @@ static int kvm_vm_ioctl_set_irqchip(struct kvm *kvm, struct kvm_irqchip *chip)
 		kvm_set_ioapic(kvm, &chip->chip.ioapic);
 		break;
 	default:
-		r = -EINVAL;
-		break;
+		return -EINVAL;
 	}
 	kvm_pic_update_irq(pic);
-	return r;
+	return 0;
 }
 
 static int kvm_vm_ioctl_get_pit(struct kvm *kvm, struct kvm_pit_state *ps)
-- 
2.18.2