From: Mark Rutland <mark.rutland@arm.com>
To: Ionela Voinescu <ionela.voinescu@arm.com>
Cc: catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
sudeep.holla@arm.com, will@kernel.org, morten.rasmussen@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: abort counter_read_on_cpu() when irqs_disabled()
Date: Fri, 13 Nov 2020 17:30:12 +0000 [thread overview]
Message-ID: <20201113173012.GD44988@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20201113165843.GA6973@arm.com>
On Fri, Nov 13, 2020 at 04:58:43PM +0000, Ionela Voinescu wrote:
> On Friday 13 Nov 2020 at 16:02:34 (+0000), Mark Rutland wrote:
> > On Fri, Nov 13, 2020 at 03:53:28PM +0000, Ionela Voinescu wrote:
> > > Given that smp_call_function_single() can deadlock when interrupts are
> > > disabled, abort the SMP call if irqs_disabled(). This scenario is
> > > currently not possible given the function's uses, but safeguard this for
> > > potential future uses.
> >
> > Sorry to contradict earlier feedback, but I think this is preferable
> > as-is, since smp_call_function_single() will
> > WARN_ON_ONCE(irqs_disabled())), but this will silently mask any dodgy
> > usage.
>
> Probably it only contradicts the chosen implementation.
>
> >
> > If we want a separate check here, I reckon we should wrap it with a
> > WARN_ON_ONCE(), and only relax that if/when we have a legitimate case
> > for calling this with IRQs disabled.
> >
>
> That's fair. I'll replace the condition below with:
>
> if (!cpu_has_amu_feat(cpu))
> return -EOPNOTSUPP;
>
> if (WARN_ON_ONCE(irqs_disabled())
> return -EPERM;
That'd be great, thanks!
With that, feel free to add:
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
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next prev parent reply other threads:[~2020-11-13 17:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 12:53 [PATCH v4 0/3] arm64: cppc: add FFH support using AMUs Ionela Voinescu
2020-11-06 12:53 ` [PATCH v4 1/3] arm64: wrap and generalise counter read functions Ionela Voinescu
2020-11-13 14:11 ` Sudeep Holla
2020-11-06 12:53 ` [PATCH v4 2/3] arm64: split counter validation function Ionela Voinescu
2020-11-13 14:12 ` Sudeep Holla
2020-11-06 12:53 ` [PATCH v4 3/3] arm64: implement CPPC FFH support using AMUs Ionela Voinescu
2020-11-12 18:00 ` Catalin Marinas
2020-11-13 12:28 ` Ionela Voinescu
2020-11-13 12:54 ` Catalin Marinas
2020-11-13 14:16 ` Sudeep Holla
2020-11-13 16:37 ` Ionela Voinescu
2020-11-13 20:03 ` Catalin Marinas
2020-11-13 15:53 ` [PATCH] arm64: abort counter_read_on_cpu() when irqs_disabled() Ionela Voinescu
2020-11-13 16:02 ` Mark Rutland
2020-11-13 16:58 ` Ionela Voinescu
2020-11-13 17:30 ` Mark Rutland [this message]
2020-11-13 19:55 ` Catalin Marinas
2020-11-13 20:26 ` [PATCH v4 0/3] arm64: cppc: add FFH support using AMUs Catalin Marinas
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