linux-kernel - Re: [PATCH v2 6/7] arm64: entry: centralize premeption decision

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Date:   Fri, 4 Feb 2022 18:46:34 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, ardb@...nel.org,
        bp@...en8.de, dave.hansen@...ux.intel.com, frederic@...nel.org,
        james.morse@....com, joey.gouly@....com, juri.lelli@...hat.com,
        linux-kernel@...r.kernel.org, luto@...nel.org, mingo@...hat.com,
        peterz@...radead.org, tglx@...utronix.de,
        valentin.schneider@....com, will@...nel.org
Subject: Re: [PATCH v2 6/7] arm64: entry: centralize premeption decision

On Fri, Feb 04, 2022 at 03:05:56PM +0000, Mark Rutland wrote:
> For historical reasons, the decision of whether or not to preempt is
> spread across arm64_preempt_schedule_irq() and __el1_irq(), and it would
> be clearer if this were all in one place.
> 
> Also, arm64_preempt_schedule_irq() calls lockdep_assert_irqs_disabled(),
> but this is redundant, as we have a subsequent identical assertion in
> __exit_to_kernel_mode(), and preempt_schedule_irq() will
> BUG_ON(!irqs_disabled()) anyway.
> 
> This patch removes the redundant assertion and centralizes the
> preemption decision making within arm64_preempt_schedule_irq().
> 
> Other than the slight change to assertion behaviour, there should be no
> functional change as a result of this patch.
> 
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: James Morse <james.morse@....com>
> Cc: Joey Gouly <joey.gouly@....com>
> Cc: Valentin Schneider <valentin.schneider@....com>
> Cc: Will Deacon <will@...nel.org>

Acked-by: Catalin Marinas <catalin.marinas@....com>