netdev - Re: [PATCH] ptp: free ptp clock properly

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Message-ID: <20200305105802.GD267906@xps-13>
Date:   Thu, 5 Mar 2020 11:58:02 +0100
From:   Andrea Righi <andrea.righi@...onical.com>
To:     Vladis Dronov <vdronov@...hat.com>
Cc:     Richard Cochran <richardcochran@...il.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ptp: free ptp clock properly

On Thu, Mar 05, 2020 at 05:47:34AM -0500, Vladis Dronov wrote:
> Hello, Andrea, all,
> 
> > > I would guess that a kernel in question (5.3.0-40-generic) has the commit
> > > a33121e5487b but does not have the commit 75718584cb3c, which should be
> > > exactly fixing a docking station disconnect crash. Could you please,
> > > check this?
> > 
> > Unfortunately the kernel in question already has 75718584cb3c:
> > https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/commit/?h=hwe&id=c71b774732f997ef38ed7bd62e73891a01f2bbfe
> > 
> > It looks like there's something else that can free up too early the
> > resources required by posix_clock_unregister() to destroy the related
> > sysfs files.
> > 
> > Maybe what we really need to call from ptp_clock_release() is
> > pps_unregister_source()? Something like this:
> 
> Err... I believe, "Maybe" is not a good enough reason to accept a kernel patch.
> Probably, there should be something supporting this statement.

Indeed. :) I've asked the original bug reporter to repeat the test with
this patch. Let's see if we can still reproduce the failure...

Thanks,
-Andrea