linux-kernel - Re: [PATCH 16/16] PCI: vmd: Switch to msi_create_parent_irq

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Message-ID: <7d8cfcf5-08db-4712-a98f-2cbfb9beeb85@mandelbit.com>
Date: Wed, 16 Jul 2025 21:52:05 +0200
From: Antonio Quartulli <antonio@...delbit.com>
To: Nam Cao <namcao@...utronix.de>, Marc Zyngier <maz@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kwilczynski@...nel.org>,
 Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 Karthikeyan Mitran <m.karthikeyan@...iveil.co.in>,
 Hou Zhiqiang <Zhiqiang.Hou@....com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, Pali Rohár
 <pali@...nel.org>, "K . Y . Srinivasan" <kys@...rosoft.com>,
 Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
 Dexuan Cui <decui@...rosoft.com>, Joyce Ooi <joyce.ooi@...el.com>,
 Jim Quinlan <jim2101024@...il.com>,
 Nicolas Saenz Julienne <nsaenz@...nel.org>,
 Florian Fainelli <florian.fainelli@...adcom.com>,
 Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>, Ray Jui <rjui@...adcom.com>,
 Scott Branden <sbranden@...adcom.com>, Ryder Lee <ryder.lee@...iatek.com>,
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 Nirmal Patel <nirmal.patel@...ux.intel.com>,
 Jonathan Derrick <jonathan.derrick@...ux.dev>,
 Matthias Brugger <matthias.bgg@...il.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 linux-arm-kernel@...ts.infradead.org, linux-hyperv@...r.kernel.org,
 linux-rpi-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH 16/16] PCI: vmd: Switch to msi_create_parent_irq_domain()

Hi Nam,

On 26/06/2025 16:48, Nam Cao wrote:
[...]
> -static void vmd_msi_free(struct irq_domain *domain,
> -			struct msi_domain_info *info, unsigned int virq)
> +static void vmd_msi_free(struct irq_domain *domain, unsigned int virq, unsigned int nr_irqs)
>   {
>   	struct vmd_irq *vmdirq = irq_get_chip_data(virq);
>   
> -	synchronize_srcu(&vmdirq->irq->srcu);
> +	for (int i = 0; i < nr_irqs; ++i) {
> +		synchronize_srcu(&vmdirq->irq->srcu);
>   
> -	/* XXX: Potential optimization to rebalance */
> -	scoped_guard(raw_spinlock_irq, &list_lock)
> -		vmdirq->irq->count--;
> +		/* XXX: Potential optimization to rebalance */
> +		scoped_guard(raw_spinlock_irq, &list_lock)
> +			vmdirq->irq->count--;
>   
> -	kfree(vmdirq);
> +		kfree(vmdirq);
> +	}

By introducing a for loop in this function, you are re-using vmdirq 
after free'ing it.

I can't send a patch because I am not faimliar with this API and I don't 
know how to fix it.

However, the issue was reported today by Coverity.

Any idea? :-)

Regards,

-- 
Antonio Quartulli

CEO and Co-Founder
Mandelbit Srl
https://www.mandelbit.com