[PATCH] KVM: x86/i8259: Remove a dead store of irq in a conditional block

[PATCH] KVM: x86/i8259: Remove a dead store of irq in a conditional block

[Like Xu]

From: Like Xu <likexu@tencent.com>

The [clang-analyzer-deadcode.DeadStores] helper reports
that the value stored to 'irq' is never read.

Signed-off-by: Like Xu <likexu@tencent.com>
---
Note: not sure if "irq2 + 8" should be needed for "s->pics[0].irq_base + irq"

 arch/x86/kvm/i8259.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index be99dc86293d..e1bb6218bb96 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -252,7 +252,6 @@ int kvm_pic_read_irq(struct kvm *kvm)
 				 */
 				irq2 = 7;
 			intno = s->pics[1].irq_base + irq2;
-			irq = irq2 + 8;
 		} else
 			intno = s->pics[0].irq_base + irq;
 	} else {
-- 
2.35.1

Re: [PATCH] KVM: x86/i8259: Remove a dead store of irq in a conditional block

[Sean Christopherson]

On Tue, Mar 01, 2022, Like Xu wrote:
> From: Like Xu <likexu@tencent.com>
> 
> The [clang-analyzer-deadcode.DeadStores] helper reports
> that the value stored to 'irq' is never read.
> 
> Signed-off-by: Like Xu <likexu@tencent.com>

Reviewed-by: Sean Christopherson <seanjc@google.com>

> ---
> Note: not sure if "irq2 + 8" should be needed for "s->pics[0].irq_base + irq"

Nope, IRQ 2 is used to cascade PIC controllers, and the two controllers have separate
vector offsets/bases.  The code was there in the original commit, 85f455f7ddbe ("KVM:
Add support for in-kernel PIC emulation"), best guess is that it was leftover from
development, e.g. maybe a flawed assumption the the second PIC's vector was simply +8?

Re: [PATCH] KVM: x86/i8259: Remove a dead store of irq in a conditional block

[Paolo Bonzini]

Queued, thanks.

Paolo