linux-kernel - [PATCH] PCI: apple: Initialize pcie->nvecs before using it

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Date:   Sat, 11 Mar 2023 14:34:53 +0100
From:   Sven Peter <sven@...npeter.dev>
To:     Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Marc Zyngier <maz@...nel.org>
Cc:     Sven Peter <sven@...npeter.dev>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        asahi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH] PCI: apple: Initialize pcie->nvecs before using it

apple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of
MSIs available for each port. It is however called before apple_msi_init
which actually initializes pcie->nvecs.
Luckily, pcie->nvecs is part of kzalloc-ed structure and thus
initialized as zero. ilog2(0) happens to be 0xffffffff which then just
configures more MSIs in hardware than we actually have. This doesn't
break anything because we never hand out those vectors.
Let's swap the order of the two calls so that we use the correctly
initialized value.

Fixes: 476c41ed4597 ("PCI: apple: Implement MSI support")
Signed-off-by: Sven Peter <sven@...npeter.dev>
---
 drivers/pci/controller/pcie-apple.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 66f37e403a09..8b7b084cf287 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 	cfg->priv = pcie;
 	INIT_LIST_HEAD(&pcie->ports);
 
+	ret = apple_msi_init(pcie);
+	if (ret)
+		return ret;
+
 	for_each_child_of_node(dev->of_node, of_port) {
 		ret = apple_pcie_setup_port(pcie, of_port);
 		if (ret) {
@@ -792,7 +796,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
 		}
 	}
 
-	return apple_msi_init(pcie);
+	return 0;
 }
 
 static int apple_pcie_probe(struct platform_device *pdev)
-- 
2.25.1