Re: [PATCH v3 1/4] PCI: sysfs: Define device attributes with DEVICE_ATTR* - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Kelsey <skunberg.kelsey@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org,
	Ruslan Bilovol <ruslan.bilovol@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Shuah Khan <skhan@linuxfoundation.org>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Bodong Wang <bodong@mellanox.com>,
	Don Dutile <ddutile@redhat.com>,
	rbilovol@cisco.com
Subject: Re: [PATCH v3 1/4] PCI: sysfs: Define device attributes with DEVICE_ATTR*
Date: Tue, 24 Mar 2020 07:24:22 +0100	[thread overview]
Message-ID: <20200324062422.GA1977781@kroah.com> (raw)
In-Reply-To: <CAFVqi1T1Fipajca8exrzs6uQAorSZeke80LYy43aCBpT45nFdA@mail.gmail.com>

On Tue, Mar 24, 2020 at 12:10:33AM -0600, Kelsey wrote:
> On Sat, Mar 14, 2020 at 5:20 AM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Sat, Mar 14, 2020 at 12:51:47PM +0200, Ruslan Bilovol wrote:
> > > On Thu, Aug 15, 2019 at 7:01 PM Kelsey Skunberg
> > > <skunberg.kelsey@gmail.com> wrote:
> > > >
> > > > Defining device attributes should be done through the helper
> > > > DEVICE_ATTR_RO(), DEVICE_ATTR_WO(), or similar. Change all instances using
> > > > __ATTR* to now use its equivalent DEVICE_ATTR*.
> > > >
> > > > Example of old:
> > > >
> > > > static struct device_attribute dev_name_##_attr=__ATTR_RO(_name);
> > > >
> > > > Example of new:
> > > >
> > > > static DEVICE_ATTR_RO(_name);
> > > >
> > > > Signed-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com>
> > > > ---
> > > >  drivers/pci/pci-sysfs.c | 59 +++++++++++++++++++----------------------
> > > >  1 file changed, 27 insertions(+), 32 deletions(-)
> > > >
> > > > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> > > > index 965c72104150..8af7944fdccb 100644
> > > > --- a/drivers/pci/pci-sysfs.c
> > > > +++ b/drivers/pci/pci-sysfs.c
> > > > @@ -464,9 +464,7 @@ static ssize_t dev_rescan_store(struct device *dev,
> > > >         }
> > > >         return count;
> > > >  }
> > > > -static struct device_attribute dev_rescan_attr = __ATTR(rescan,
> > > > -                                                       (S_IWUSR|S_IWGRP),
> > > > -                                                       NULL, dev_rescan_store);
> > > > +static DEVICE_ATTR(rescan, (S_IWUSR | S_IWGRP), NULL, dev_rescan_store);
> > > >
> > > >  static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
> > > >                             const char *buf, size_t count)
> > > > @@ -480,9 +478,8 @@ static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
> > > >                 pci_stop_and_remove_bus_device_locked(to_pci_dev(dev));
> > > >         return count;
> > > >  }
> > > > -static struct device_attribute dev_remove_attr = __ATTR_IGNORE_LOCKDEP(remove,
> > > > -                                                       (S_IWUSR|S_IWGRP),
> > > > -                                                       NULL, remove_store);
> > > > +static DEVICE_ATTR_IGNORE_LOCKDEP(remove, (S_IWUSR | S_IWGRP), NULL,
> > > > +                                 remove_store);
> > > >
> > > >  static ssize_t dev_bus_rescan_store(struct device *dev,
> > > >                                     struct device_attribute *attr,
> > > > @@ -504,7 +501,7 @@ static ssize_t dev_bus_rescan_store(struct device *dev,
> > > >         }
> > > >         return count;
> > > >  }
> > > > -static DEVICE_ATTR(rescan, (S_IWUSR|S_IWGRP), NULL, dev_bus_rescan_store);
> > > > +static DEVICE_ATTR(bus_rescan, (S_IWUSR | S_IWGRP), NULL, dev_bus_rescan_store);
> > >
> > > This patch renamed 'rescan' to 'bus_rescan' and broke my userspace application.
> > > There is also mismatch now between real functionality and documentation
> > > Documentation/ABI/testing/sysfs-bus-pci which still contains old "rescan"
> > > descriptions.
> > >
> > > Another patch from this patch series also renamed 'rescan' to 'dev_rescan'
> > >
> > > Here is a comparison between two stable kernels (with and without this
> > > patch series):
> > >
> > > v5.4
> > > # find /sys -name '*rescan'
> > > /sys/devices/pci0000:00/0000:00:01.2/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:01.0/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:04.0/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:00.0/dev_rescan
> > > /sys/devices/pci0000:00/pci_bus/0000:00/bus_rescan
> > > /sys/devices/pci0000:00/0000:00:01.3/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:03.0/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:01.1/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:02.0/dev_rescan
> > > /sys/devices/pci0000:00/0000:00:05.0/dev_rescan
> > > /sys/bus/pci/rescan
> > >
> > > v4.19
> > > # find /sys -name '*rescan'
> > > /sys/devices/pci0000:00/0000:00:01.2/rescan
> > > /sys/devices/pci0000:00/0000:00:01.0/rescan
> > > /sys/devices/pci0000:00/0000:00:04.0/rescan
> > > /sys/devices/pci0000:00/0000:00:00.0/rescan
> > > /sys/devices/pci0000:00/pci_bus/0000:00/rescan
> > > /sys/devices/pci0000:00/0000:00:01.3/rescan
> > > /sys/devices/pci0000:00/0000:00:03.0/rescan
> > > /sys/devices/pci0000:00/0000:00:01.1/rescan
> > > /sys/devices/pci0000:00/0000:00:02.0/rescan
> > > /sys/devices/pci0000:00/0000:00:05.0/rescan
> > > /sys/bus/pci/rescan
> > >
> > > Do we maintain this kind of API as non-changeable?
> >
> > Yeah, that's a bug and should be fixed, sorry for missing that on
> > review.
> >
> > Kelsey, can you fix this up?
> >
> > thanks,
> >
> > greg k-h
> 
> I'd be happy to help get this fixed up.
> 
> Would it be proper to go back to using DEVICE_ATTR() for 'bus_rescan'
> and 'dev_rescan' in order to change their names back to 'rescan'?

Yes.

thanks,

greg k-h