Messages in this thread | | | Date | Thu, 23 Jun 2022 09:13:08 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH v6 32/33] arm64: irq-gic: Replace unreachable() with -EINVAL |
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On 2022-06-23 02:49, Chen Zhongjin wrote: > Using unreachable() at default of switch generates an extra branch at > end of the function, and compiler won't generate a ret to close this > branch because it knows it's unreachable. > > If there's no instruction in this branch, compiler will generate a NOP, > And it will confuse objtool to warn this NOP as a fall through branch. > > In fact these branches are actually unreachable, so we can replace > unreachable() with returning a -EINVAL value. > > Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com> > --- > arch/arm64/kvm/hyp/vgic-v3-sr.c | 7 +++---- > drivers/irqchip/irq-gic-v3.c | 2 +- > 2 files changed, 4 insertions(+), 5 deletions(-)
Basic courtesy would have been to Cc the maintainers of this code.
> > diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c > b/arch/arm64/kvm/hyp/vgic-v3-sr.c > index 4fb419f7b8b6..f3cee92c3038 100644 > --- a/arch/arm64/kvm/hyp/vgic-v3-sr.c > +++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c > @@ -6,7 +6,6 @@ > > #include <hyp/adjust_pc.h> > > -#include <linux/compiler.h> > #include <linux/irqchip/arm-gic-v3.h> > #include <linux/kvm_host.h> > > @@ -55,7 +54,7 @@ static u64 __gic_v3_get_lr(unsigned int lr) > return read_gicreg(ICH_LR15_EL2); > } > > - unreachable(); > + return -EINVAL;
NAK. That's absolutely *wrong*, and will hide future bugs. Nothing checks for -EINVAL, and we *never* expect to reach this, hence the perfectly valid annotation.
If something needs fixing, it probably is your tooling.
M. -- Jazz is not dead. It just smells funny...
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