> -----Original Message----- > From: Jakub Kicinski [mailto:kubak...@wp.pl] > Sent: Tuesday, November 28, 2017 8:08 PM > To: Kirsher, Jeffrey T <jeffrey.t.kirs...@intel.com> > Cc: mi...@redhat.com; pet...@infradead.org; Keller, Jacob E > <jacob.e.kel...@intel.com>; linux-kernel@vger.kernel.org; > net...@vger.kernel.org; nhor...@redhat.com; sassm...@redhat.com; > jogre...@redhat.com; luca abeni <luca.ab...@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.kel...@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.kel...@intel.com> > > Cc: luca abeni <luca.ab...@santannapisa.it> > > Tested-by: Andrew Bowers <andrewx.bow...@intel.com> > > Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.com> > > This is already in Linus's tree (I've been waiting for it to land as > well :)) >
Excellent. Regards, Jake
