linux-kernel - RE: [patch 06/20] genirq/msi: Check for invalid MSI parent domain usage

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Message-ID: <87tu2wjw5q.ffs@tglx>
Date:   Fri, 18 Nov 2022 13:15:45 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Tian, Kevin" <kevin.tian@...el.com>,
        LKML <linux-kernel@...r.kernel.org>
Cc:     "x86@...nel.org" <x86@...nel.org>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        "Raj, Ashok" <ashok.raj@...el.com>, Jon Mason <jdmason@...zu.us>,
        Allen Hubbe <allenbh@...il.com>,
        "Ahmed S. Darwish" <darwi@...utronix.de>,
        "Chatre, Reinette" <reinette.chatre@...el.com>
Subject: RE: [patch 06/20] genirq/msi: Check for invalid MSI parent domain
 usage

On Fri, Nov 18 2022 at 07:50, Kevin Tian wrote:
>> From: Thomas Gleixner <tglx@...utronix.de>
>> Sent: Friday, November 11, 2022 9:57 PM
>> 
>> @@ -937,13 +937,21 @@ int msi_domain_alloc_irqs_descs_locked(s
>> 
>>  	lockdep_assert_held(&dev->msi.data->mutex);
>> 
>> +	if (WARN_ON_ONCE(irq_domain_is_msi_parent(domain))) {
>> +		ret = -EINVAL;
>> +		goto free;
>> +	}
>> +
>> +	/* Frees allocated descriptors in case of failure. */
>>  	ret = msi_domain_add_simple_msi_descs(info, dev, nvec);
>>  	if (ret)
>>  		return ret;
>
> it's unusual to see a direct return when error unwind is already required
> at an early failure point. is it something which can be improved here?

It's redundant in this case, but you are right it looks weird.