Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   "Keller, Jacob E" <jacob.e.keller@intel.com>
To:     Jakub Kicinski <kubakici@wp.pl>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>
CC:     "mingo@redhat.com" <mingo@redhat.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "nhorman@redhat.com" <nhorman@redhat.com>,
        "sassmann@redhat.com" <sassmann@redhat.com>,
        "jogreene@redhat.com" <jogreene@redhat.com>,
        luca abeni <luca.abeni@santannapisa.it>
Subject: RE: [PATCH] sched/deadline: fix one-bit signed bitfields to be
 unsigned
Thread-Topic: [PATCH] sched/deadline: fix one-bit signed bitfields to be
 unsigned
Thread-Index: AQHTaIi86QA4rSCuNkq3qoNlQFZQcaMrREyAgADKPdA=
Date:   Thu, 30 Nov 2017 00:12:09 +0000
Message-ID: <02874ECE860811409154E81DA85FBB5882AFAB96@ORSMSX115.amr.corp.intel.com>
References: <20171128203619.71430-1-jeffrey.t.kirsher@intel.com>
 <20171128200726.1c806eb7@cakuba.netronome.com>
In-Reply-To: <20171128200726.1c806eb7@cakuba.netronome.com>
Accept-Language: en-US
Content-Language: en-US
dlp-product: dlpe-windows
dlp-version: 11.0.0.116
dlp-reaction: no-action
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 8BIT
MIME-Version: 1.0
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

> -----Original Message-----
> From: Jakub Kicinski [mailto:kubakici@wp.pl]
> Sent: Tuesday, November 28, 2017 8:08 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@intel.com>
> Cc: mingo@redhat.com; peterz@infradead.org; Keller, Jacob E
> <jacob.e.keller@intel.com>; linux-kernel@vger.kernel.org;
> netdev@vger.kernel.org; nhorman@redhat.com; sassmann@redhat.com;
> jogreene@redhat.com; luca abeni <luca.abeni@santannapisa.it>
> Subject: Re: [PATCH] sched/deadline: fix one-bit signed bitfields to be unsigned
> 
> On Tue, 28 Nov 2017 12:36:19 -0800, Jeff Kirsher wrote:
> > From: Jacob Keller <jacob.e.keller@intel.com>
> >
> > Commit 799ba82de01e ("sched/deadline: Use C bitfields for the state
> > flags", 2017-10-10) introduced the use of C bitfields for these
> > variables. However, sparse complains about them:
> >
> > ./include/linux/sched.h:476:62: error: dubious one-bit signed bitfield
> > ./include/linux/sched.h:477:62: error: dubious one-bit signed bitfield
> > ./include/linux/sched.h:478:62: error: dubious one-bit signed bitfield
> > ./include/linux/sched.h:479:62: error: dubious one-bit signed bitfield
> >
> > This is because a one-bit signed bitfield can only hold the values 0 and
> > -1, which can cause problems if the program expects to be able to
> > represent the value positive 1.
> >
> > In practice, this may not cause a bug since -1 would be considered
> > "true" in logical tests, however we should avoid the practice anyways.
> >
> > Fixes: 799ba82de01e ("sched/deadline: Use C bitfields for the state flags", 2017-
> 10-10)
> > Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
> > Cc: luca abeni <luca.abeni@santannapisa.it>
> > Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
> > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> 
> This is already in Linus's tree (I've been waiting for it to land as
> well :))
> 

Excellent.

Regards,
Jake

From 1585371976993302527@xxx Wed Nov 29 04:08:56 +0000 2017
X-GM-THRID: 1585343607967539974
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread