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Date: Fri, 10 Apr 2026 20:13:38 +0900
From: Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kwilczynski@kernel.org>
To: Ilpo =?utf-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>, Bjorn Helgaas <helgaas@kernel.org>,
	Manivannan Sadhasivam <mani@kernel.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Magnus Lindholm <linmag7@gmail.com>,
	Matt Turner <mattst88@gmail.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	Christophe Leroy <chleroy@kernel.org>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Dexuan Cui <decui@microsoft.com>,
	Krzysztof =?utf-8?Q?Ha=C5=82asa?= <khalasa@piap.pl>,
	Lukas Wunner <lukas@wunner.de>,
	Oliver O'Halloran <oohall@gmail.com>,
	Saurabh Singh Sengar <ssengar@microsoft.com>,
	Shuan He <heshuan@bytedance.com>,
	Srivatsa Bhat <srivatsabhat@microsoft.com>,
	linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 06/20] PCI/sysfs: Convert PCI resource files to static
 attributes
Message-ID: <20260410111338.GB1750802@rocinante>
References: <20260410055040.39233-1-kwilczynski@kernel.org>
 <20260410055040.39233-7-kwilczynski@kernel.org>
 <4fc23ce0-7103-545b-bc11-230b52c2de94@linux.intel.com>
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In-Reply-To: <4fc23ce0-7103-545b-bc11-230b52c2de94@linux.intel.com>

Hello,

> > -	/* Expose the PCI resources from this device as files */
> > -	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> > +	if (!pci_resource_len(pdev, bar))
> > +		return 0;
> 
> I know it's same as in the previous code but I dislike assuming len != 0 
> implies resource has been assigned. While it currently holds, I'd want to 
> change that eventually.
> 
> The current behavior causes issue e.g. if IOV resource fails to assign, it 
> is reset (making its len 0 among other thing) and since IOV resource are 
> optional that is fine from kernel's perspective. But resetting the 
> resource means we also lose access to that resource because its type gets 
> cleared so from kernel perspective the VF BAR stops to exist. Losing it 
> means the user cannot solve the issue by e.g. resizing some other BAR 
> smaller to make space to allow the VF BARs to assign successfully.
> 
> So I think this code would actually want to check resource_assigned() 
> which implies also non-zero size.

Makes sense.

I will update the code to use resource_assigned().  Since we are working on
this code anyway, it would be only prudent to also do the right thing.

> AFAICT, this change looks fine (despite the diff being very messy).

Thank you!

	Krzysztof