linux-kernel - Re: [PATCH v2 1/2] PCI: endpoint: pci-epf-test: Make use of cached 'epc_features' in pci_epf_test_core

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Date: Thu, 18 Apr 2024 10:29:20 +0200
From: Niklas Cassel <cassel@...nel.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Krzysztof Wilczyński <kw@...ux.com>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH v2 1/2] PCI: endpoint: pci-epf-test: Make use of cached
 'epc_features' in pci_epf_test_core_init()

On Thu, Apr 18, 2024 at 01:29:58PM +0530, Manivannan Sadhasivam wrote:
> Instead of getting the epc_features from pci_epc_get_features() API, use
> the cached pci_epf_test::epc_features value to avoid the NULL check. Since
> the NULL check is already performed in pci_epf_test_bind(), having one more
> check in pci_epf_test_core_init() is redundant and it is not possible to
> hit the NULL pointer dereference.
> 
> Also with commit a01e7214bef9 ("PCI: endpoint: Remove "core_init_notifier"
> flag"), 'epc_features' got dereferenced without the NULL check, leading to
> the following false positive smatch warning:
> 
> drivers/pci/endpoint/functions/pci-epf-test.c:784 pci_epf_test_core_init()
> error: we previously assumed 'epc_features' could be null (see line 747)
> 
> So let's remove the redundant NULL check and also use the epc_features::
> {msix_capable/msi_capable} flags directly to avoid local variables.
> 
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/linux-pci/024b5826-7180-4076-ae08-57d2584cca3f@moroto.mountain/
> Fixes: 5e50ee27d4a5 ("PCI: pci-epf-test: Add support to defer core initialization")
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---

Reviewed-by: Niklas Cassel <cassel@...nel.org>