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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Tyrel Datwyler <tyreld@linux.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 124/190] powerpc/pseries: extract host bridge from pci_bus prior to bus removal
Date:   Thu, 20 May 2021 11:23:08 +0200
Message-Id: <20210520092106.302333187@linuxfoundation.org>
In-Reply-To: <20210520092102.149300807@linuxfoundation.org>
References: <20210520092102.149300807@linuxfoundation.org>
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From: Tyrel Datwyler <tyreld@linux.ibm.com>

[ Upstream commit 38d0b1c9cec71e6d0f3bddef0bbce41d05a3e796 ]

The pci_bus->bridge reference may no longer be valid after
pci_bus_remove() resulting in passing a bad value to device_unregister()
for the associated bridge device.

Store the host_bridge reference in a separate variable prior to
pci_bus_remove().

Fixes: 7340056567e3 ("powerpc/pci: Reorder pci bus/bridge unregistration during PHB removal")
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210211182435.47968-1-tyreld@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/platforms/pseries/pci_dlpar.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/pci_dlpar.c b/arch/powerpc/platforms/pseries/pci_dlpar.c
index 5d4a3df59d0c..baaeb753fa79 100644
--- a/arch/powerpc/platforms/pseries/pci_dlpar.c
+++ b/arch/powerpc/platforms/pseries/pci_dlpar.c
@@ -98,6 +98,7 @@ EXPORT_SYMBOL_GPL(init_phb_dynamic);
 int remove_phb_dynamic(struct pci_controller *phb)
 {
 	struct pci_bus *b = phb->bus;
+	struct pci_host_bridge *host_bridge = to_pci_host_bridge(b->bridge);
 	struct resource *res;
 	int rc, i;
 
@@ -124,7 +125,8 @@ int remove_phb_dynamic(struct pci_controller *phb)
 	/* Remove the PCI bus and unregister the bridge device from sysfs */
 	phb->bus = NULL;
 	pci_remove_bus(b);
-	device_unregister(b->bridge);
+	host_bridge->bus = NULL;
+	device_unregister(&host_bridge->dev);
 
 	/* Now release the IO resource */
 	if (res->flags & IORESOURCE_IO)
-- 
2.30.2