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From: Justin Stitt <justinstitt@google.com>
To: Linus Walleij <linus.walleij@linaro.org>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	 Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org,
	linux-mtd@lists.infradead.org,  linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev,  Justin Stitt <justinstitt@google.com>
Subject: [PATCH] mtd: maps: fix -Wvoid-pointer-to-enum-cast warning
Date: Tue, 15 Aug 2023 21:11:12 +0000	[thread overview]
Message-ID: <20230815-void-drivers-mtd-maps-physmap-versatile-v1-1-ba6fc86d5e4e@google.com> (raw)

When building with clang 18 I see the following warning:
|       drivers/mtd/maps/physmap-versatile.c:209:25: warning: cast to smaller
|               integer type 'enum versatile_flashprot' from 'const void *' [-Wvoid-pointer-to-enum-cast]
|         209 |                 versatile_flashprot = (enum versatile_flashprot)devid->data;

This is due to the fact that `devid->data` is a void* while `enum
versatile_flashprot` 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@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Note: There is likely no data loss occurring here due to the fact that
`enum versatile_flashprot` has only a few enumerated fields, none of
which are large enough to cause data loss. Nonetheless, this patch helps
towards the goal of eventually enabling this warning for more builds.

Signed-off-by: Justin Stitt <justinstitt@google.com>
---
 drivers/mtd/maps/physmap-versatile.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/maps/physmap-versatile.c b/drivers/mtd/maps/physmap-versatile.c
index a1b8b7b25f88..d65cf8833771 100644
--- a/drivers/mtd/maps/physmap-versatile.c
+++ b/drivers/mtd/maps/physmap-versatile.c
@@ -206,7 +206,7 @@ int of_flash_probe_versatile(struct platform_device *pdev,
 		if (!sysnp)
 			return -ENODEV;
 
-		versatile_flashprot = (enum versatile_flashprot)devid->data;
+		versatile_flashprot = (uintptr_t)devid->data;
 		rmap = syscon_node_to_regmap(sysnp);
 		of_node_put(sysnp);
 		if (IS_ERR(rmap))

---
base-commit: 2ccdd1b13c591d306f0401d98dedc4bdcd02b421
change-id: 20230815-void-drivers-mtd-maps-physmap-versatile-2270fe7fdf16

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


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             reply	other threads:[~2023-08-15 21:11 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-15 21:11 Justin Stitt [this message]
2023-08-15 21:15 ` [PATCH] mtd: maps: fix -Wvoid-pointer-to-enum-cast warning Krzysztof Kozlowski
2023-08-15 23:06   ` Justin Stitt
2023-08-16  5:34     ` Krzysztof Kozlowski

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