linux-kernel - Re: [PATCH v2] iommu/tegra241-cmdqv: do not use smp_processor

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Message-Id: <173378751166.2164111.11293401851587446576.b4-ty@kernel.org>
Date: Tue, 10 Dec 2024 00:17:28 +0000
From: Will Deacon <will@...nel.org>
To: Thierry Reding <thierry.reding@...il.com>,
	Krishna Reddy <vdumpa@...dia.com>,
	Robin Murphy <robin.murphy@....com>,
	Joerg Roedel <joro@...tes.org>,
	Jonathan Hunter <jonathanh@...dia.com>,
	linux-kernel@...r.kernel.org,
	iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-tegra@...r.kernel.org,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-rt-devel@...ts.linux.dev,
	"Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
Cc: catalin.marinas@....com,
	kernel-team@...roid.com,
	Will Deacon <will@...nel.org>
Subject: Re: [PATCH v2] iommu/tegra241-cmdqv: do not use smp_processor_id in preemptible context

On Fri, 06 Dec 2024 10:01:14 -0300, Luis Claudio R. Goncalves wrote:
> During boot some of the calls to tegra241_cmdqv_get_cmdq() will happen
> in preemptible context. As this function calls smp_processor_id(), if
> CONFIG_DEBUG_PREEMPT is enabled, these calls will trigger a series of
> "BUG: using smp_processor_id() in preemptible" backtraces.
> 
> As tegra241_cmdqv_get_cmdq() only calls smp_processor_id() to use the
> CPU number as a factor to balance out traffic on cmdq usage, it is safe
> to use raw_smp_processor_id() here.
> 
> [...]

Applied to will (for-joerg/arm-smmu/fixes), thanks!

[1/1] iommu/tegra241-cmdqv: do not use smp_processor_id in preemptible context
      https://git.kernel.org/will/c/1f806218164d

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
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