Re: USB Attached SCSI breakage due no udev involvement

From: Greg KH <gregkh@linuxfoundation.org>
To: Dio Putra <dioput12@gmail.com>
Cc: oneukum@suse.com, linux-usb@vger.kernel.org,
	linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net,
	stern@rowland.harvard.edu, linux-kernel@vger.kernel.org
Subject: Re: USB Attached SCSI breakage due no udev involvement
Date: Sun, 10 May 2020 09:32:58 +0200	[thread overview]
Message-ID: <20200510073258.GA3474912@kroah.com> (raw)
In-Reply-To: <e409bbfe-c446-2ba3-423d-c6e198abef33@gmail.com>

On Sun, May 10, 2020 at 02:10:04PM +0700, Dio Putra wrote:
> On 5/10/20 1:54 PM, Greg KH wrote:
> > On Sun, May 10, 2020 at 01:48:24PM +0700, Dio Putra wrote:
> >> On 5/10/20 12:47 PM, Greg KH wrote:
> >>> On Sun, May 10, 2020 at 09:55:57AM +0700, Dio Putra wrote:
> >>>> Hi, it's first time for me to report user-space breakage in here, so
> >>>> i'm begging your pardon.
> >>>>
> >>>> I want to report that Linux 5.4 breaking my USB mount workflow due
> >>>> udevadm monitor report here (I'm using vanilla kernel 5.4.39 on
> >>>> Slackware64 Current and vanilla kernel 4.4.221 on Slackware64 14.2):
> >>>
> >>> <snip>
> >>>
> >>> Sorry, but what actually changed that you can see in the logs?
> >> Sorry, what do you mean? The dmesg log or the kernel changelogs?
> > 
> > Either, your message made them pretty impossible to compare with all of
> > the line-wrapping :(
> > 
> I'm so sorry for first message mess, because that message has been sent by
> Gmail Website. Can I send my logs as attachment? I try to convenient everyone
> here. ( FYI, I just switched to Thunderbird with these settings:
> https://www.kernel.org/doc/html/v4.12/process/email-clients.html#thunderbird-gui ) 

Sure, attachments work, but better yet, if you can show the difference
in a few lines that is much nicer than having to dig through large
numbers of log files.

> >>> What functionality broke?  What used to work that no longer does work?
> >>>
> >> Yes, it supposed that just work and kernel could talk with udev, not just handled by the kernel.
> > 
> > I don't understand, what functionality changed?  What exactly used to
> > work that no longer does?
> linux-5.4 has been never called the udev dependencies whereas
> linux-4.4 will call any udev dependencies if necessary, that's the problem.

I do not understand what exactly you mean by "call udev dependencies".

udev is used to create symlinks and set user/group permissions on device
nodes in /dev/ which is created by devtmpfs.  What exactly is not
happening in your /dev/ with the move to a newer kernel?

> > Did you change anything else other than the kernel on your system?  Did
> > you change to a newer version of udev/systemd or anything else?
> > 
> I'm using eudev-master from their official mirror github:
> https://github.com/gentoo/eudev

Have you contacted the eudev developers to see if something different
needs to be set in your kernel when moving 4 years in kernel development
forward?  Are you sure you have all the correct config options enabled?

Why such a huge leap forward all at once, how about going from 4.4.y to
4.9.y and then 4.14.y and then 5.4.y?  That might help narrow things
down a bit easier.

thanks,

greg k-h