Re: [BUG, PATCH 03/10] sysfs: added __compat_only_sysfs_link_entry_to_kobj()

From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Jeremiah Mahler <jmmahler@gmail.com>,
	tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org,
	peterhuewe@gmx.de, gregkh@linuxfoundation.org,
	jgunthorpe@obsidianresearch.com, dhowells@redhat.com,
	artem.bityutskiy@linux.intel.com, Tejun Heo <tj@kernel.org>,
	NeilBrown <neilb@suse.de>, Guenter Roeck <linux@roeck-us.net>,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [BUG, PATCH 03/10] sysfs: added __compat_only_sysfs_link_entry_to_kobj()
Date: Sun, 8 Nov 2015 02:49:06 +0200	[thread overview]
Message-ID: <20151108004906.GA25843@intel.com> (raw)
In-Reply-To: <20151107231147.GA9273@newt.localdomain>

On Sat, Nov 07, 2015 at 03:11:47PM -0800, Jeremiah Mahler wrote:
> Jarkko,
> 
> On Sun, Nov 08, 2015 at 12:31:09AM +0200, Jarkko Sakkinen wrote:
> > On Sat, Nov 07, 2015 at 10:08:56AM -0800, Jeremiah Mahler wrote:
> > > Jarkko,
> > > 
> > > On Sat, Nov 07, 2015 at 01:41:37PM +0200, Jarkko Sakkinen wrote:
> > > > On Sat, Nov 07, 2015 at 12:55:43PM +0200, Jarkko Sakkinen wrote:
> > > > > On Fri, Nov 06, 2015 at 06:55:18PM -0800, Jeremiah Mahler wrote:
> > > > > > Jarkko,
> > > > > > 
> [...]
> > > > I pushed a fix over here:
> > > > 
> > > > https://github.com/jsakkine/linux-tpmdd/tree/fixes
> > > > 
> > > This fix does work since it effectively avoids the call to
> > > __compat_only_sysfs_link_entry_to_kobj().
> > > 
> > > Have you tested cases where __compat_only_sysfs_link_entry_to_kobj()
> > > is actually used?
> > 
> > Yes, of course I have. And I checked your DSDT and my assumption was
> > correct. There was no DSM in the ACPI object.
> > 
> > However, there is probably another regression but it is caused by some
> > patch that was added earlier. I strongly believe it is not caused by any
> > of my 4.4 patches.
> > 
> > I think what was happening with you was that
> > __compat_only_sysfs_link_entry_to_kobj() was returning -ENOENT, which it
> > should do when target is not found. This was propagated to tpm_tis and
> > it probably messes up clean up somehow.
> > 
> > I have to test my hypothesis as soon as possible. The fix that I pushed
> > is still valid no matter which way the things are.
> > 
> > > [...]
> > > 
> > > -- 
> > > - Jeremiah Mahler
> > 
> > /Jarkko
> 
> It sounds like you have the problem figured out and have a good fix.
> If I can do anything else to help let me know :-)

Turns out that after all the second issue that I described was also
because of this patch.

Clean up was not done properly when that function. I revised my fix.

If you want to help, check that the revised patch works I'll add
Tested-by to the patch. Thank you!

> -- 
> - Jeremiah Mahler

/Jarkko