linux-kernel - Re: [PATCH] genirq: Avoid race between cpu hot plug and irq

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Message-ID: <alpine.DEB.2.21.1809052022110.1416@nanos.tec.linutronix.de>
Date:   Wed, 5 Sep 2018 20:23:57 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Prakruthi Deepak Heragu <pheragu@...eaurora.org>
cc:     linux-kernel@...r.kernel.org, ckadabi@...eaurora.org,
        tsoni@...eaurora.org, bryanh@...eaurora.org,
        Prasad Sodagudi <psodagud@...eaurora.org>
Subject: Re: [PATCH] genirq: Avoid race between cpu hot plug and irq_desc()
 allocation paths

On Wed, 5 Sep 2018, Prakruthi Deepak Heragu wrote:

> One of the cores might have just allocated irq_desc() and other core
> might be doing irq migration in the hot plug path. In the hot plug path
> during the IRQ migration, for_each_active_irq macro is trying to get
> irqs whose bits are set in allocated_irqs bit map but there is no return
> value check after irq_to_desc for desc validity.

Confused. All parts involved, irq allocation/deallocation and the CPU
hotplug code take sparse_irq_lock to prevent exavtly that.

Thanks,

	tglx