linux-kernel - [PATCH] PCI: iproc: fix -Wvoid-pointer-to-enum-cast warning

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Message-ID: <20230814-void-drivers-pci-controller-pcie-iproc-platform-v1-1-81a121607851@google.com>
Date:   Mon, 14 Aug 2023 22:29:22 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        "Krzysztof Wilczyński" <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] PCI: iproc: fix -Wvoid-pointer-to-enum-cast warning

When building with clang 18 I see the following warning:
|       drivers/pci/controller/pcie-iproc-platform.c:55:15: warning: cast to smaller
|                integer type 'enum iproc_pcie_type' from 'const void *' [-Wvoid-pointer-to-enum-cast]
|          55 |         pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);

This is due to the fact that `of_device_get_match_data` returns a void*
while `enum iproc_pcie_type` has the size of an int. This leads to
truncation and possible data loss.

Link: https://github.com/ClangBuiltLinux/linux/issues/1910
Reported-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: There is likely no data loss occurring here since `enum
iproc_pcie_type` has only a few fields enumerated from 0. Definitely not
enough to cause data loss from pointer-width to int-width.
---
 drivers/pci/controller/pcie-iproc-platform.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-iproc-platform.c b/drivers/pci/controller/pcie-iproc-platform.c
index acdc583d2980..83cbc95f4384 100644
--- a/drivers/pci/controller/pcie-iproc-platform.c
+++ b/drivers/pci/controller/pcie-iproc-platform.c
@@ -52,7 +52,7 @@ static int iproc_pltfm_pcie_probe(struct platform_device *pdev)
 	pcie = pci_host_bridge_priv(bridge);
 
 	pcie->dev = dev;
-	pcie->type = (enum iproc_pcie_type) of_device_get_match_data(dev);
+	pcie->type = (uintptr_t) of_device_get_match_data(dev);
 
 	ret = of_address_to_resource(np, 0, &reg);
 	if (ret < 0) {

---
base-commit: 2ccdd1b13c591d306f0401d98dedc4bdcd02b421
change-id: 20230814-void-drivers-pci-controller-pcie-iproc-platform-ada4ac9a9a75

Best regards,
--
Justin Stitt <justinstitt@...gle.com>