linux-kernel - Re: [PATCH v13 02/13] irqchip/sifive-plic: Improve locking safety by using irqsave/irqrestore

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Date: Wed, 21 Feb 2024 19:05:52 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Frank Rowand <frowand.list@...il.com>, 
	Conor Dooley <conor+dt@...nel.org>, Marc Zyngier <maz@...nel.org>, Björn Töpel <bjorn@...nel.org>, 
	Atish Patra <atishp@...shpatra.org>, Andrew Jones <ajones@...tanamicro.com>, 
	Sunil V L <sunilvl@...tanamicro.com>, Saravana Kannan <saravanak@...gle.com>, 
	Anup Patel <anup@...infault.org>, linux-riscv@...ts.infradead.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	devicetree@...r.kernel.org
Subject: Re: [PATCH v13 02/13] irqchip/sifive-plic: Improve locking safety by
 using irqsave/irqrestore

On Tue, Feb 20, 2024 at 3:41 PM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> On Tue, Feb 20 2024 at 11:37, Anup Patel wrote:
> > Now that PLIC driver is probed as a regular platform driver, the lock
> > dependency validator complains about the safety of handler->enable_lock
> > usage:
> >
> > [    0.956775]  Possible interrupt unsafe locking scenario:
> >
> > [    0.956998]        CPU0                    CPU1
> > [    0.957247]        ----                    ----
> > [    0.957439]   lock(&handler->enable_lock);
> > [    0.957607]                                local_irq_disable();
> > [    0.957793]                                lock(&irq_desc_lock_class);
> > [    0.958021]                                lock(&handler->enable_lock);
> > [    0.958246]   <Interrupt>
> > [    0.958342]     lock(&irq_desc_lock_class);
> > [    0.958501]
> >                 *** DEADLOCK ***
> >
> > To address above, let's use raw_spin_lock_irqsave/unlock_irqrestore()
> > instead of raw_spin_lock/unlock().
>
> s/let's//

Okay, I will update.

Regards,
Anup