linux-kernel - [RFC 3/5] PCI: hv: Set NULL as the ACPI device for the PCI host bridge

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Date:   Wed, 11 Aug 2021 23:36:17 +0800
From:   Boqun Feng <boqun.feng@...il.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Boqun Feng <boqun.feng@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-hyperv@...r.kernel.org,
        Sunil Muthuswamy <sunilmut@...rosoft.com>,
        Marc Zyngier <maz@...nel.org>, Arnd Bergmann <arnd@...db.de>
Subject: [RFC 3/5] PCI: hv: Set NULL as the ACPI device for the PCI host bridge

A PCI host bridge of Hyper-V doesn't have the corresponding ACPI device,
therefore a NULL pointer needs to be set as the ->private of
pci_host_bridge since for platforms with ACPI ->private is used to store
the ACPI device information for the host bridges.

And since kzalloc() is used to allocate pci_host_bridge, as a result,
what is needed is just setting the correct size of ->private, kzalloc()
will zero the field as if set a NULL pointer to it.

Signed-off-by: Boqun Feng <boqun.feng@...il.com>
---
 drivers/pci/controller/pci-hyperv.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 62dbe98d1fe1..fd3792b5edcc 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3021,7 +3021,12 @@ static int hv_pci_probe(struct hv_device *hdev,
 	 */
 	BUILD_BUG_ON(sizeof(*hbus) > HV_HYP_PAGE_SIZE);
 
-	bridge = devm_pci_alloc_host_bridge(&hdev->device, 0);
+	/*
+	 * devm_pci_alloc_host_bridge() use kzalloc(), and we want to set
+	 * ->private as a NULL pointer, therefore no need to set ->private after
+	 * allocation.
+	 */
+	bridge = devm_pci_alloc_host_bridge(&hdev->device, sizeof(struct acpi_device *));
 	if (!bridge)
 		return -ENOMEM;
 
-- 
2.32.0