From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Jiri Kosina <jikos@kernel.org>,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
linux-input@vger.kernel.org
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: [PATCH v1] HID: core: don't use negative operands when shift
Date: Tue, 13 Jun 2017 12:22:22 +0300 [thread overview]
Message-ID: <20170613092222.4073-1-andriy.shevchenko@linux.intel.com> (raw)
From: Andy Shevchenko <andy.shevchenko@gmail.com>
The recent C standard in 6.5.7 paragraph 4 defines that operands for
bitwise shift operators should be non-negative, otherwise it's an
undefined behaviour.
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
drivers/hid/hid-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 5f87dbe28336..73416fef983e 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1046,7 +1046,7 @@ static s32 snto32(__u32 value, unsigned n)
case 16: return ((__s16)value);
case 32: return ((__s32)value);
}
- return value & (1 << (n - 1)) ? value | (-1 << n) : value;
+ return value & (1 << (n - 1)) ? value | (~0U << n) : value;
}
s32 hid_snto32(__u32 value, unsigned n)
--
2.11.0
next reply other threads:[~2017-06-13 9:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-13 9:22 Andy Shevchenko [this message]
2017-06-13 9:59 ` [PATCH v1] HID: core: don't use negative operands when shift Benjamin Tissoires
2017-06-13 12:29 ` Jiri Kosina
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