[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 7 Jul 2022 16:22:10 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Nicolin Chen <nicolinc@...dia.com>
Cc: "Tian, Kevin" <kevin.tian@...el.com>,
"kwankhede@...dia.com" <kwankhede@...dia.com>,
"corbet@....net" <corbet@....net>,
"hca@...ux.ibm.com" <hca@...ux.ibm.com>,
"gor@...ux.ibm.com" <gor@...ux.ibm.com>,
"agordeev@...ux.ibm.com" <agordeev@...ux.ibm.com>,
"borntraeger@...ux.ibm.com" <borntraeger@...ux.ibm.com>,
"svens@...ux.ibm.com" <svens@...ux.ibm.com>,
"zhenyuw@...ux.intel.com" <zhenyuw@...ux.intel.com>,
"Wang, Zhi A" <zhi.a.wang@...el.com>,
"jani.nikula@...ux.intel.com" <jani.nikula@...ux.intel.com>,
"joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
"Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
"tvrtko.ursulin@...ux.intel.com" <tvrtko.ursulin@...ux.intel.com>,
"airlied@...ux.ie" <airlied@...ux.ie>,
"daniel@...ll.ch" <daniel@...ll.ch>,
"farman@...ux.ibm.com" <farman@...ux.ibm.com>,
"mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
"pasic@...ux.ibm.com" <pasic@...ux.ibm.com>,
"vneethv@...ux.ibm.com" <vneethv@...ux.ibm.com>,
"oberpar@...ux.ibm.com" <oberpar@...ux.ibm.com>,
"freude@...ux.ibm.com" <freude@...ux.ibm.com>,
"akrowiak@...ux.ibm.com" <akrowiak@...ux.ibm.com>,
"jjherne@...ux.ibm.com" <jjherne@...ux.ibm.com>,
"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
"cohuck@...hat.com" <cohuck@...hat.com>,
"hch@...radead.org" <hch@...radead.org>,
"jchrist@...ux.ibm.com" <jchrist@...ux.ibm.com>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
"intel-gvt-dev@...ts.freedesktop.org"
<intel-gvt-dev@...ts.freedesktop.org>,
"intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFT][PATCH v2 1/9] vfio: Make vfio_unpin_pages() return void
On Thu, Jul 07, 2022 at 10:12:41AM -0700, Nicolin Chen wrote:
> On Thu, Jul 07, 2022 at 08:42:28AM +0000, Tian, Kevin wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > > From: Nicolin Chen <nicolinc@...dia.com>
> > > Sent: Wednesday, July 6, 2022 2:28 PM
> > >
> > > There's only one caller that checks its return value with a WARN_ON_ONCE,
> > > while all other callers do not check return value at all. So simplify the
> > > API to return void by embedding similar WARN_ON_ONCEs.
> >
> > While this change keeps the similar effect as before it leads to different
> > policy for same type of errors between pin and unpin paths:
>
> I think it's because of the policy that an undo function should not
> fail. Meanwhile, indulging faulty inputs isn't good either.
>
> > e.g.
> >
> > vfio_unpin_pages():
> > if (WARN_ON_ONCE(!user_pfn || !npage || !vfio_assert_device_open(device)))
> > return;
> >
> > vfio_pin_pages():
> > if (!user_pfn || !phys_pfn || !npage ||
> > !vfio_assert_device_open(device))
> > return -EINVAL;
> >
> > It sounds a bit weird when reading related code...
>
> Any better way to handle this?
They should all be WARN_ON's, that is the standard pattern to assert
that function arguments must be correctly formed.
I would also drop the tests that obviously will oops on their on
anyone, like NULL pointer checks. This is a semi-performance path.
Jason
Powered by blists - more mailing lists