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From: Arnd Bergmann <arnd@kernel.org>
To: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Pierre Ossman" <pierre@ossman.eu>
Cc: Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Subject: [PATCH] cb710: avoid NULL pointer subtraction
Date: Mon, 27 Sep 2021 14:13:57 +0200	[thread overview]
Message-ID: <20210927121408.939246-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.de>

clang-14 complains about an unusual way of converting a pointer to
an integer:

drivers/misc/cb710/sgbuf2.c:50:15: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction]
        return ((ptr - NULL) & 3) != 0;

Replace this with a normal cast to uintptr_t.

Fixes: 5f5bac8272be ("mmc: Driver for CB710/720 memory card reader (MMC part)")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/misc/cb710/sgbuf2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/cb710/sgbuf2.c b/drivers/misc/cb710/sgbuf2.c
index e5a4ed3701eb..a798fad5f03c 100644
--- a/drivers/misc/cb710/sgbuf2.c
+++ b/drivers/misc/cb710/sgbuf2.c
@@ -47,7 +47,7 @@ static inline bool needs_unaligned_copy(const void *ptr)
 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 	return false;
 #else
-	return ((ptr - NULL) & 3) != 0;
+	return ((uintptr_t)ptr & 3) != 0;
 #endif
 }
 
-- 
2.29.2


             reply	other threads:[~2021-09-27 12:14 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 12:13 Arnd Bergmann [this message]
2021-09-27 15:31 ` [PATCH] cb710: avoid NULL pointer subtraction Michał Mirosław

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