linux-kernel - Re: [PATCH 037/190] Revert "RDMA/core: Fix several reference count leaks."

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Message-ID: <YIq24bDyB49QJm0S@kroah.com>
Date:   Thu, 29 Apr 2021 15:38:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     linux-kernel@...r.kernel.org, Qiushi Wu <wu000273@....edu>
Subject: Re: [PATCH 037/190] Revert "RDMA/core: Fix several reference count
 leaks."

On Wed, Apr 28, 2021 at 10:00:44AM -0300, Jason Gunthorpe wrote:
> On Wed, Apr 28, 2021 at 02:23:40PM +0200, Greg Kroah-Hartman wrote:
> 
> > > We've talked about this specifically before:
> > > 
> > > http://lore.kernel.org/r/20210331170720.GY2710221@ziepe.ca
> > > 
> > > I still don't understand what you mean by "udev sees it properly", as
> > > above, all the tests I thought of look OK.
> > 
> > Can you query the udev database to see the attribute values?
> 
> It appears so unless I misunderstand your ask:
> 
> $ udevadm info -a /sys/class/infiniband/ibp0s9
>     ATTR{ports/1/cm_rx_duplicates/dreq}=="0"

That works?  Nice, I didn't think it did.

But what about the uevent that fired for "1", isn't there attibutes
assigned to it that udev ignores?

> > As you say, it's uABI for now, so odds are nothing can be changed.  It's
> > just no fun for when other subsystems want to do this same thing, they
> > point at this code and say "see, they did it!" :)
> 
> Are you sure we shouldn't just formally support this?
> 
> What is the exact technical blocker?

Placing a raw kobject below a struct device breaks the "device tree"
model.  You now have devices with an arbritrary number of levels deep
set of attributes, making it impossible to determine all attributes for
a device in a simple way.

thanks,

greg k-h