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From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Tian, Kevin" <kevin.tian@intel.com>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     "x86@kernel.org" <x86@kernel.org>, Joerg Roedel <joro@8bytes.org>,
        Will Deacon <will@kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Marc Zyngier <maz@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jason Gunthorpe <jgg@mellanox.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        "Williams, Dan J" <dan.j.williams@intel.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        "Raj, Ashok" <ashok.raj@intel.com>, Jon Mason <jdmason@kudzu.us>,
        Allen Hubbe <allenbh@gmail.com>,
        "Ahmed S. Darwish" <darwi@linutronix.de>,
        "Chatre, Reinette" <reinette.chatre@intel.com>
Subject: RE: [patch 06/20] genirq/msi: Check for invalid MSI parent domain
 usage
In-Reply-To: <BN9PR11MB52761A0C8124248D78076B3F8C099@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <20221111131813.914374272@linutronix.de>
 <20221111132706.388892782@linutronix.de>
 <BN9PR11MB52761A0C8124248D78076B3F8C099@BN9PR11MB5276.namprd11.prod.outlook.com>
Date:   Fri, 18 Nov 2022 13:15:45 +0100
Message-ID: <87tu2wjw5q.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Fri, Nov 18 2022 at 07:50, Kevin Tian wrote:
>> From: Thomas Gleixner <tglx@linutronix.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.