linux-kernel - Re: pci driver loads right after unload

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Date:   Tue, 2 Jan 2018 20:27:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     Max Gurtovoy <maxg@...lanox.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: pci driver loads right after unload

On Tue, Jan 02, 2018 at 01:00:03PM -0600, Bjorn Helgaas wrote:
> [+cc Greg, linux-kernel]
> 
> Hi Max,
> 
> Thanks for the report!
> 
> On Tue, Jan 02, 2018 at 01:50:23AM +0200, Max Gurtovoy wrote:
> > hi all,
> > I encountered a strange phenomena using 2 different pci drivers
> > (nvme and mlx5_core) since 4.15-rc1:
> > when I try to unload the modules using "modprobe -r" cmd it calls
> > the .probe function right after calling the .remove function and the
> > module is not realy unloaded.
> > I think there is some race condition because when I added a
> > msleep(1000) after "pci_unregister_driver(&nvme_driver);" (in the
> > nvme module testing, it also worked in the mlx5_core), the issue
> > seems to dissapear.
> 
> You say "since 4.15-rc1".  Does that mean it's a regression?  If so,
> what's the most recent kernel that does not have this problem?  Worst
> case, you could bisect to find where it broke.
> 
> I don't see anything obvious in the drivers/pci changes between v4.14
> and v4.15-rc1.  Module loading and driver binding is mostly driven by
> the driver core and udev.  Maybe you could learn something with
> "udevadm monitor" or by turning on the some of the debug in
> lib/kobject_uevent.c?


This should be resolved in 4.15-rc6, there was a regression in -rc1 in
this area when dealing with uevents over netlink.

Max, can you test -rc6 to verify if this is really fixed or not?

thanks,

greg k-h