linux-kernel - Re: [PATCH v3 6/7] arm64: entry: centralize premeption decision

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Message-ID: <YgTYcmrKAmHzU2im@FVFF77S0Q05N>
Date:   Thu, 10 Feb 2022 09:19:10 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Catalin Marinas <catalin.marinas@....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 v3 6/7] arm64: entry: centralize premeption decision

On Wed, Feb 09, 2022 at 06:10:52PM +0000, Catalin Marinas wrote:
> On Wed, Feb 09, 2022 at 03:35:34PM +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>
> 
> I acked this patch in v2, has anything changed? Well, here it is again:

Sorry; I had meant to add your acks.

This patch is the same as in v2; the other patch has some minor changes as in
the cover letter (adding includes and always exposing a couple of function
prototypes).

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

Thanks!

> BTW, you have a typo in the subject.

I'll go fix that now.

Mark.