From: Maxime Coquelin <maxime.coquelin@st.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: <gong.chen@linux.intel.com>, Ingo Molnar <mingo@kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, <tytso@mit.edu>,
<linux-kernel@vger.kernel.org>, <stable@vger.kernel.org>,
<kernel@stlinux.com>, <eric.paire@st.com>
Subject: Re: [PATCH v2] bitops: Fix shift overflow in GENMASK macros
Date: Tue, 4 Nov 2014 11:47:33 +0100 [thread overview]
Message-ID: <5458AEC5.5020606@st.com> (raw)
In-Reply-To: <20141104104414.GL3337@twins.programming.kicks-ass.net>
On 11/04/2014 11:44 AM, Peter Zijlstra wrote:
> On Tue, Nov 04, 2014 at 11:03:57AM +0100, Maxime COQUELIN wrote:
>
>> -#define GENMASK(h, l) (((U32_C(1) << ((h) - (l) + 1)) - 1) << (l))
>> -#define GENMASK_ULL(h, l) (((U64_C(1) << ((h) - (l) + 1)) - 1) << (l))
>> +#define GENMASK(h, l) ((~0UL >> (BITS_PER_LONG - (h - l + 1))) << l)
>> +#define GENMASK_ULL(h, l) ((~0ULL >> (BITS_PER_LONG_LONG - (h - l + 1))) << l)
> OK, so you need to keep the (h) and (l) bits, macro arguments should be
> wrapped in seemingly superfluous braces in order to preserve precedence
> on expansion.
You're right, I should have seen this..
>
> My bad for not explicitly doing that when suggesting the alternative.
Not a problem, v3 is coming.
Maxime
prev parent reply other threads:[~2014-11-04 10:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 10:03 [PATCH v2] bitops: Fix shift overflow in GENMASK macros Maxime COQUELIN
2014-11-04 10:44 ` Peter Zijlstra
2014-11-04 10:47 ` Maxime Coquelin [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5458AEC5.5020606@st.com \
--to=maxime.coquelin@st.com \
--cc=eric.paire@st.com \
--cc=gong.chen@linux.intel.com \
--cc=kernel@stlinux.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=stable@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.