From: Benjamin Tissoires <benjamin.tissoires@redhat.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jiri Kosina <jikos@kernel.org>,
linux-input@vger.kernel.org,
Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: Re: [PATCH v1] HID: core: don't use negative operands when shift
Date: Tue, 13 Jun 2017 11:59:27 +0200 [thread overview]
Message-ID: <20170613095927.GC29589@mail.corp.redhat.com> (raw)
In-Reply-To: <20170613092222.4073-1-andriy.shevchenko@linux.intel.com>
On Jun 13 2017 or thereabouts, Andy Shevchenko wrote:
> 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>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.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 prev parent reply other threads:[~2017-06-13 9:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-13 9:22 [PATCH v1] HID: core: don't use negative operands when shift Andy Shevchenko
2017-06-13 9:59 ` Benjamin Tissoires [this message]
2017-06-13 12:29 ` Jiri Kosina
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