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SubjectRe: [PATCH 12/14] sparc64: rtrap: Remove unneeded need_resched() loop
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From: Valentin Schneider <valentin.schneider@arm.com>
Date: Mon, 11 Mar 2019 22:47:50 +0000

> Since the enabling and disabling of IRQs within preempt_schedule_irq()
> is contained in a need_resched() loop, we don't need the outer arch
> code loop.
>
> We seem to be looping back somewhere much higher than the usual
> preempt/need_resched checks, but AFAICT we would just branch to
> 'rtrap_no_irq_enable' and then back to 'to_kernel', which is
> a need_resched() loop with a few extra steps.
>
> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: sparclinux@vger.kernel.org
> ---
> arch/sparc/kernel/rtrap_64.S | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S
> index 29aa34f11720..57fb75686957 100644
> --- a/arch/sparc/kernel/rtrap_64.S
> +++ b/arch/sparc/kernel/rtrap_64.S
> @@ -322,7 +322,6 @@ to_kernel:
> nop
> call preempt_schedule_irq
> nop
> - ba,pt %xcc, rtrap
> #endif
> kern_fpucheck: ldub [%g6 + TI_FPDEPTH], %l5
> brz,pt %l5, rt_continue
> --
> 2.20.1
>

We must re-evaluate the %tstate value stored in ptregs, you cannot
make this change.

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