2021-03-22 03:56:29

by xuyihang

Subject: [PATCH -next] x86: Fix unused variable 'hi'

Fixes the following W=1 kernel build warning(s):
arch/x86/hyperv/hv_apic.c:58:15: warning: variable ‘hi’ set but not used [-Wunused-but-set-variable]

Compiled with CONFIG_HYPERV enabled:
make allmodconfig ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu-
make W=1 arch/x86/hyperv/hv_apic.o ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu-

HV_X64_MSR_EOI stores on bit 31:0 and HV_X64_MSR_TPR stores in bit 7:0, which means higher 32 bits are not really used, therefore __maybe_unused added.

Reported-by: Hulk Robot <[email protected]>
Signed-off-by: Xu Yihang <[email protected]>
---
arch/x86/hyperv/hv_apic.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index 284e73661a18..c0b0a5774f31 100644
--- a/arch/x86/hyperv/hv_apic.c
+++ b/arch/x86/hyperv/hv_apic.c
@@ -55,7 +55,8 @@ static void hv_apic_icr_write(u32 low, u32 id)

static u32 hv_apic_read(u32 reg)
{
- u32 reg_val, hi;
+ u32 hi __maybe_unused;
+ u32 reg_val;

switch (reg) {
case APIC_EOI:
--
2.17.1

2021-03-22 11:04:30

by Wei Liu

Subject: Re: [PATCH -next] x86: Fix unused variable 'hi'

On Mon, Mar 22, 2021 at 11:54:26AM +0800, Xu Yihang wrote:
> Fixes the following W=1 kernel build warning(s):
> arch/x86/hyperv/hv_apic.c:58:15: warning: variable ‘hi’ set but not used [-Wunused-but-set-variable]
>
> Compiled with CONFIG_HYPERV enabled:
> make allmodconfig ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu-
> make W=1 arch/x86/hyperv/hv_apic.o ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu-
>
> HV_X64_MSR_EOI stores on bit 31:0 and HV_X64_MSR_TPR stores in bit 7:0, which means higher 32 bits are not really used, therefore __maybe_unused added.
>
> Reported-by: Hulk Robot <[email protected]>
> Signed-off-by: Xu Yihang <[email protected]>

I slightly modified the commit message and queued it up for hyperv-next.
Thanks.

Wei.