Re: [RFC PATCH v3 5/8] ata_dev_printk: Use dev_printk

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jul 14, 2020 at 10:06:05AM +0200, Bartlomiej Zolnierkiewicz wrote:
> 
> Hi Tony,
> 
> On 7/9/20 11:18 PM, Tony Asleson wrote:
> > Hi Bartlomiej,
> > 
> > On 6/24/20 5:35 AM, Bartlomiej Zolnierkiewicz wrote:
> >> The root source of problem is that libata transport uses different
> >> naming scheme for ->tdev devices (please see dev_set_name() in
> >> ata_t{dev,link,port}_add()) than libata core for its logging
> >> functionality (ata_{dev,link,port}_printk()).
> >>
> >> Since libata transport is part of sysfs ABI we should be careful
> >> to not break it so one idea for solving the issue is to convert
> >> ata_t{dev,link,port}_add() to use libata logging naming scheme and
> >> at the same time add sysfs symlinks for the old libata transport
> >> naming scheme.

Given the age of the current implementation, what suddenly broke that
requires this to change at this point in time?

> > 
> > I tried doing as you suggested.  I've included what I've done so far.  I
> > haven't been able to get all the needed parts for the symlinks to
> > maintain compatibility.
> > 
> > The /sys/class/.. seems OK, eg.
> > 
> > $  ls -x -w 70 /sys/class/ata_[dl]*
> > /sys/class/ata_device:
> > ata1.00  ata2.00  ata3.00  ata4.00  ata5.00  ata6.00  ata7.00
> > ata7.01  ata8.00  ata8.01  dev1.0   dev2.0   dev3.0   dev4.0
> > dev5.0   dev6.0   dev7.0   dev7.1   dev8.0   dev8.1
> > 
> > /sys/class/ata_link:
> > ata1   ata2   ata3   ata4   ata5   ata6   ata7  ata8  link1  link2
> > link3  link4  link5  link6  link7  link8

A link class?  Ick ick ick.

> > but the implementation is a hack, see device.h, core.c changes.  There
> > must be a better way?
> > 
> > Also I'm missing part of the full path, eg.
> > 
> > /sys/devices/pci0000:00/0000:00:01.1/ata7/link7/dev7.0/ata_device/dev7.0/gscr
> > 
> > becomes
> > 
> > /sys/devices/pci0000:00/0000:00:01.1/ata7/ata7/ata7.01/ata_device/ata7.01/gscr
> > 
> > but the compatibility symlinks added only get me to
> > 
> > /sys/devices/pci0000:00/0000:00:01.1/ata7/link7/dev7.0/ata_device/
> > 
> > I haven't found the right spot to get the last symlink included.
> > 
> > If you or anyone else has suggestions to correct the incomplete symlink
> > and/or correct the implementation to set the
> > /sys/class/ata_device it would be greatly appreciated.

I can't understand what you are trying to do here.

What do you want to represent in sysfs with a symlink that you can't
just have in a single sysfs file like "name" or "new_name" or
"name_because_we_didnt_think_about_this_10_years_ago" that shows you the
other "name" that you are trying to look up here?

Why abuse symlinks like this at all?

And no, the device.h and core.c changes aren't ok :)

thanks,

greg k-h